CN207282509U - The crystalline silicon of double-side photic/film silicon heterojunction solar battery - Google Patents

Abstract

The utility model provides a crystalline silicon/thin-film silicon heterojunction solar cell receiving light on both sides, comprising: an n-type silicon substrate; a window layer including intrinsic amorphous silicon or microcrystalline silicon with a wide optical band gap and n type doped amorphous silicon or microcrystalline silicon; the back field layer, including intrinsic amorphous silicon or microcrystalline silicon and p-type doped amorphous silicon or microcrystalline silicon; the first transparent conductive film; the second transparent conductive a thin film; a first electrode; and a second electrode. The double-sided light-receiving solar cell of the utility model uses intrinsic amorphous silicon or microcrystalline silicon with a wide optical band gap and low defect density and n-type amorphous silicon or microcrystalline silicon film stacks as the window layer, effectively reducing the window layer The defect density can reduce the absorption loss of sunlight, and improve the photoelectric conversion efficiency and power output of solar cells and photovoltaic modules. Compared with the existing HIT battery, the utility model has a wider process window, which is beneficial to the process control and management of mass production.

Description

Crystalline Silicon/Thin Film Silicon Heterojunction Solar Cells Received Light on Both Sides

technical field

The utility model belongs to the photovoltaic field of photoelectric conversion, in particular to a crystal silicon/thin film silicon heterojunction solar cell receiving light on both sides and a manufacturing method thereof.

Background technique

A solar cell is a photoelectric conversion device whose basic characteristic is to receive sunlight and convert it directly into electrical energy. The basic structure of a solar cell is a large-area p-n junction composed of two semiconductor materials of different conductivity types. The semiconductor material has a high absorption capacity for sunlight, and the internal electric field of the p-n junction separates the photogenerated carriers generated by the semiconductor material. That is, electron-hole pairs form potential barriers, collect and export carriers through metal electrodes, and form electricity. In order to improve the ability of solar cells to absorb light, the surface of semiconductor materials is usually made into a concave-convex structure. Through multiple refraction and multiple absorption of sunlight, the reflection of sunlight on the surface is reduced. At the same time, a dielectric with anti-reflection function is made on the surface. Or other optical film materials, that is, surface anti-reflection film, to further reduce the optical loss caused by surface reflection and improve the ability to absorb sunlight.

Solar cells are mainly made of crystalline silicon, which is processed and manufactured using semiconductor technology. First, use chemical reagents or physical methods to corrode or etch the surface of crystalline silicon to make a regular pyramid structure, use gaseous or solid-state diffusion to make a p-n junction on the surface, deposit an optical film on the front surface to reduce the reflection loss of sunlight, and finally make Metal electrodes complete the processing of the basic structure of solar cells.

In order to obtain power output, effectively protect solar cells, and adapt to large-scale installations, metal wires or metal strips are usually used to connect multiple solar cells in series or in parallel, and then use high-transmittance glass on the front surface that receives sunlight. The back side uses a polymer resin material with good sealing performance, and a packaging material with strong adhesive and sealing properties is added between the glass, battery and back plate to combine the glass, battery and back plate to make multiple A power generation unit composed of batteries, namely photovoltaic modules. In order to facilitate handling and installation, as well as have a certain bearing capacity and wind resistance, a metal frame is usually installed on the edge of the module.

With the development and large-scale application of solar cell technology, great changes have taken place in solar cell materials and structures. In addition to crystalline silicon solar cells, solar cells of various compound materials have appeared, such as gallium arsenide (GaAs) , copper indium gallium selenide (CIGS), cadmium telluride (CdTe), etc. Most of these solar cells are not composed of p-n junctions of the same material, that is, homojunction (homojunction) solar cells, but a heterojunction (Heterojunction) p-n junction structure composed of these light-absorbing materials and other materials. In the series of silicon materials, in addition to the initial monocrystalline silicon solar cells, polycrystalline silicon and thin film silicon solar cells also appeared. Polycrystalline silicon solar cells are basically the same process technology except that the method used to make the surface concave-convex structure is different from that of monocrystalline silicon. Thin-film silicon solar cells include amorphous silicon, microcrystalline silicon, and even nano-silicon thin-film solar cells. Due to the incomplete structure of these films, there are a large number of structural defects, the most representative of which is the dangling-bond of silicon atoms that do not form bonding bonds. The solar cells formed by purely p-type and n-type films have a p-n junction. The recombination rate in the depleted region is very high, and the conversion efficiency of the cell is very low. Therefore, a solar cell with a p-i-n structure has been developed, that is, a non-doped intrinsic (Intrinsic) amorphous silicon film is added between the p and n-type film materials as a light absorbing layer, so that the carriers are in the p-n junction region. The recombination of solar cells is greatly reduced, and the conversion efficiency of solar cells is effectively improved. However, due to the change of amorphous silicon and microcrystalline silicon films under light conditions, especially after absorbing high-energy ultraviolet light, the bond between silicon and hydrogen will be cracked, which will increase the structural defects inside the film and lead to the conversion of solar cells. Efficiency drops, i.e. light-induced attenuation.

In order to solve the basic technical problems of thin-film silicon solar cells and improve the conversion efficiency of crystalline silicon solar cells, Japan Sanyo Electric Co., Ltd. combined the characteristics of amorphous silicon thin films with the surface treatment technology of crystalline silicon to research and develop The crystalline silicon heterojunction solar cell with a crystalline silicon thin film layer is expressed in English as Heterojunction with an Intrinsic Thin-layer, referred to as HIT solar cell, and in China it is mostly called SHJ solar cell, corresponding to SiliconHeterojunction. HIT battery is a crystalline silicon solar cell with extremely high conversion efficiency. The highest conversion efficiency in the laboratory reaches 25.1%, and the average conversion efficiency in mass production in Japan reaches more than 22%. The HIT structure is shown in Figure 1. Its basic structure is based on an n-type single crystal silicon wafer 30. First, it is chemically cleaned and surface textured to form a concave-convex structure on the surface that improves light absorption, which is commonly referred to as The light-trapping pyramid structure on the surface is chemically cleaned again to form a clean surface, and a stack of intrinsic amorphous silicon film 321 and p-type doped silicon-based film 322 is deposited on the front surface of the silicon wafer by plasma chemical vapor deposition (PECVD) and other methods. layer, deposit intrinsic amorphous silicon film 311 and n-type doped amorphous silicon film 312 on the back, and then deposit transparent conductive oxide (TCO) films 33 and 34 on both sides, and then make metal electrodes by screen printing technology 35, 36 form a solar cell 3 with a symmetrical structure. In use, the solar cell 3 is packaged with a metal frame 106 , an upper adhesive film 102 , a tempered glass 103 , a lower adhesive film 104 and a back plate 105 , as shown in FIG. 2 . In HIT solar cells, intrinsic amorphous silicon and doped amorphous silicon film stacks form a good passivation on the surface of crystalline silicon, separate and collect photo-generated carriers, therefore, amorphous silicon film is an important part of HIT cells , whose structure and properties are crucial to the conversion efficiency and stability of solar cells. However, due to the structural uncertainty of amorphous silicon thin films, the transition region from amorphous to microcrystalline is very large, and the obtained structure factor, optical bandgap, and electrical conductivity range are also very large, making it difficult to fabricate intrinsic amorphous silicon. And the process window of doped amorphous silicon layer is difficult to determine. Especially boron-doped p-type amorphous silicon, due to the complex decomposition process of the most commonly used raw material gas (B ₂ H ₆ ) doped with boron atoms in chemical vapor deposition, the decomposition reaction intermediate (Precusor) is difficult to control, boron Atoms and incompletely decomposed intermediates are more likely to form lattice defects in p-type amorphous silicon films. Therefore, p-type amorphous silicon generally contains higher structural defects and dangling bond densities, making p-type amorphous silicon The optical absorption of the layer and the increase of the carrier recombination rate make it difficult to control the manufacturing process of HIT batteries. It is difficult to find a process window to achieve high efficiency in the actual production process. The distribution range of battery efficiency is relatively wide, which affects the mass production of HIT batteries. and industrial promotion.

In order to solve the technical problems of the process window and process control of amorphous silicon thin films in HIT cells, especially the deposition of p-type doped amorphous silicon thin films, reduce the absorption of sunlight by the window layer and the recombination of carriers, many companies and A lot of research has been carried out by scientific research institutions, mainly focusing on the use of different amorphous silicon thin film deposition techniques, such as plasma enhanced chemical vapor deposition (PE-CVD), metal thermal catalytic chemical vapor deposition (Cat-CVD), thermal Wire chemical vapor deposition (Hot-wire CVD) technology, etc., change the deposition conditions of amorphous silicon films, including selection of process gas, plasma power density, pressure, temperature, etc., and perform post-film deposition treatments, including plasma treatment, However, these have not achieved good results, and the mass production of HIT cells still faces great difficulties. Under the background of large-scale expansion of the solar cell industry, HIT cells have not been promoted.

Utility model content

In view of the shortcomings of the prior art described above, the purpose of this utility model is to provide a double-sided light-receiving crystalline silicon/thin-film silicon heterojunction solar cell and its manufacturing method, which are used to solve the problem of p-type amorphous silicon window layer in HIT cells. The thin film manufacturing process is difficult to control, and the technical problems of high optical absorption and carrier recombination rate widen the process window of amorphous silicon thin film and improve the conversion efficiency of solar cells.

In order to achieve the above purpose and other related purposes, the utility model provides a crystalline silicon/thin film silicon heterojunction solar cell receiving light on both sides. The solar cell includes: an n-type silicon substrate, which has an opposite first surface and The second surface; the window layer, formed on the first surface of the n-type silicon substrate, which includes intrinsic amorphous silicon or microcrystalline silicon with a wide optical bandgap and n-type doped amorphous silicon or microcrystalline Silicon; the back field layer is formed on the second surface of the n-type silicon substrate, which includes intrinsic amorphous silicon or microcrystalline silicon and p-type doped amorphous silicon or microcrystalline silicon; the first transparent conductive film , formed on the surface of the window layer; a second transparent conductive film, formed on the surface of the back field layer; a first electrode, fabricated on the first transparent conductive film; and a second electrode, fabricated on the second on a transparent conductive film.

Preferably, the silicon substrate is n-type crystalline silicon.

Preferably, intrinsic amorphous silicon or microcrystalline silicon thin films are respectively deposited on the first and second surfaces of the n-type crystalline silicon substrate to form a crystalline silicon/thin film silicon heterojunction interface, using intrinsic amorphous silicon or The microcrystalline silicon forms a good passivation of the dangling bonds on the surface of the n-type crystalline silicon substrate, so that the surface recombination rate of the n-type silicon substrate is below 10 cm/s, wherein, intrinsic amorphous silicon or microcrystalline The thickness of the silicon ranges from 3 to 20 nm.

Preferably, doping oxygen atoms in the deposition of the intrinsic amorphous silicon or microcrystalline silicon film to form a silicon-oxygen film, inhibiting the crystal epitaxial growth of the amorphous silicon or microcrystalline silicon film on the surface of the n-type silicon substrate, and at the same time An intrinsic layer with high optical transmittance and low defects is obtained, wherein the doping amount of oxygen atoms is 5×10 ¹⁹ to 5×10 ²⁰ cm ^-3 .

Preferably, an n-type doped amorphous silicon or microcrystalline silicon film is deposited on the surface of the intrinsic amorphous silicon or microcrystalline silicon film on the first surface of the n-type crystalline silicon substrate, and between the n-type substrate A built-in electric field is formed, and photogenerated carriers near the first surface of the n-type crystalline silicon substrate are collected through the action of the built-in electric field, wherein the thickness of the window layer ranges from 4 to 10 nm.

Preferably, carbon atoms are doped into the n-type window layer to form an amorphous or microcrystalline silicon-carbon film, so as to reduce the defect density of the n-type window layer and expand the optical bandgap width, wherein the doping amount of carbon is 7×10 ¹⁹ ～2×10 ²⁰ cm ⁻³ .

Preferably, a p-type doped amorphous silicon or microcrystalline silicon film is deposited on the surface of the intrinsic amorphous silicon or microcrystalline silicon film on the second surface of the n-type crystalline silicon substrate, between the n-type substrate and the A built-in electric field is formed to collect photogenerated carriers near the second surface of the n-type crystalline silicon substrate through the built-in electric field, wherein the thickness of the back field layer is in the range of 4-20nm.

Preferably, the first transparent conductive film is deposited on the surface of the window layer, and the transparent conductive film has good optical transmittance, high electrical conductivity, and a suitable refractive index transparent conductive film or thin laminated material for collecting the first transparent conductive film. Carriers on one surface, while reducing the reflection loss of sunlight on the surface of the window layer, the first transparent conductive film includes tin-doped indium oxide, aluminum-doped indium oxide, tungsten-doped indium oxide, titanium-doped indium oxide, cesium-doped indium oxide Indium, aluminum-doped zinc oxide, gallium-doped zinc oxide, aluminum-gallium-doped zinc oxide, and graphene are superimposed combinations of one or more thin film materials.

Preferably, a second transparent conductive film is deposited on the surface of the back field layer, and the transparent conductive film has good electrical conductivity and high work function or a thin laminated material, which is used to provide carriers for collecting the second surface, so The second transparent conductive film includes tin-doped indium oxide, aluminum-doped indium oxide, tungsten-doped indium oxide, titanium-doped indium oxide, cesium-doped indium oxide, aluminum-doped zinc oxide, gallium-doped zinc oxide, aluminum-gallium-doped zinc oxide, graphene A superposition combination of one or more film materials.

The utility model also provides a photovoltaic module, which is formed by connecting a plurality of crystalline silicon/thin-film silicon heterojunction solar cells that receive light on both sides in series or in parallel by using metal interconnection wires or metal interconnection strips. The window layer of the solar cell faces the direction of the light-receiving surface of the photovoltaic module, and the back field layer is arranged toward the back direction of the photovoltaic module, so that the window layer of the solar cell becomes the main light-receiving surface.

Preferably, the encapsulation material on the front surface of the photovoltaic module is selected as tempered white glass or transparent resin material with high optical transmittance, low optical reflectance, and high load capacity, so as to ensure that sunlight is provided to the solar cells encapsulated inside. Irradiation, and provide loads generated by photovoltaic module transportation, installation, wind pressure, and snow accumulation.

Preferably, the back packaging material of the photovoltaic module is selected as a material with high optical reflectivity, so that the double-sided light-receiving crystalline silicon/thin-film silicon heterojunction solar cell encapsulated inside receives the reflected light of the back packaging material to obtain Photoelectric conversion efficiency and power generation gain.

Preferably, the backside packaging material of the photovoltaic module is selected as a material with high optical transmittance, so that the double-sided light-receiving crystalline silicon/thin-film silicon heterojunction solar cells encapsulated inside can receive the reflected light and scattering of the backside environment Light gains in photoelectric conversion efficiency and power generation.

Preferably, a metal frame is installed on the edge of the photovoltaic module, and a high-strength sealing material is coated to further improve the sealing and load capacity of the photovoltaic module.

The utility model also provides a method for manufacturing a crystalline silicon/thin-film silicon heterojunction solar cell receiving light on both sides, comprising the steps of: providing an n-type crystalline silicon substrate having opposite first and second surfaces; Depositing a first intrinsic amorphous silicon or microcrystalline silicon film on the first surface of the n-type crystalline silicon substrate; depositing n-type on the surface of the first intrinsic amorphous silicon or microcrystalline silicon film on the first surface doping amorphous silicon or microcrystalline silicon thin film; depositing a second intrinsic amorphous silicon or microcrystalline silicon thin film on the second surface of the n-type crystalline silicon substrate; Depositing p-type doped amorphous silicon or microcrystalline silicon film on the surface of amorphous silicon or microcrystalline silicon film; forming a first transparent conductive film on the surface of n-type doped amorphous silicon or microcrystalline silicon; forming a second transparent conductive film on the surface of p-type doped amorphous silicon or microcrystalline silicon; making a first electrode on the first transparent conductive film; making a second electrode on the second transparent conductive film.

Preferably, providing an n-type silicon substrate further includes the steps of texturing and cleaning the first surface and the second surface of the n-type silicon substrate.

Preferably, the first amorphous silicon or microcrystalline silicon thin film, the second amorphous silicon or microcrystalline silicon thin film, n-type doped amorphous silicon or microcrystalline silicon, p-type doped amorphous silicon or The method of microcrystalline silicon includes one of plasma enhanced vapor deposition method PE-CVD, metal thermal catalytic chemical vapor deposition method Cat-CVD, and hot wire chemical vapor deposition method Hot-wire CVD.

Preferably, while depositing an intrinsic amorphous silicon or microcrystalline silicon thin film on the first surface and the second surface of the n-type crystalline silicon substrate, oxygen atoms are doped to form the first and second intrinsic Amorphous or microcrystalline silicon oxygen or silicon carbon films are formed in amorphous silicon or microcrystalline silicon films.

Preferably, an n-type doped amorphous silicon or microcrystalline silicon film is deposited on the surface of the intrinsic amorphous silicon or microcrystalline silicon film located on the first surface, and carbon atoms are doped at the same time, so that the n-type doped Amorphous or microcrystalline silicon-carbon films are formed in heterogeneous amorphous silicon or microcrystalline silicon films.

Preferably, a p-type doped amorphous silicon or microcrystalline silicon film is deposited on the surface of the second amorphous silicon or microcrystalline silicon film located on the second surface.

As mentioned above, the crystalline silicon/thin film silicon heterojunction solar cell and the manufacturing method of the present invention have the following beneficial effects:

The utility model utilizes intrinsic amorphous silicon or microcrystalline silicon film to form an effective passivation effect on the surface of crystalline silicon, reduces the recombination rate of the surface of crystalline silicon, uses doped n-type amorphous silicon or microcrystalline silicon as the window layer, and uses Doping p-type amorphous silicon or microcrystalline silicon as the back field layer further improves the surface passivation effect of crystalline silicon, and at the same time collects photogenerated carriers generated by crystalline silicon. In particular, using n-type amorphous silicon or microcrystalline silicon with a wide optical bandgap and low defect density as the surface window layer can effectively reduce the carrier recombination in the window layer, and at the same time facilitate the first surface transparent conductive oxide (TCO ) film or film stack optimization to obtain an anti-reflection surface with excellent photoelectric performance, reduce the absorption loss of sunlight, especially improve the short-wave response; use doped p-type amorphous silicon or microcrystalline silicon as the back field layer, which can be passed Effectively control the conductivity and work function of p-type amorphous silicon or microcrystalline silicon thin films, and at the same time facilitate the optimization of the work function of the second surface TCO thin film or thin film stack to reduce or even eliminate the TCO of p-type amorphous silicon or microcrystalline silicon The Schottky barrier formed when the thin films are in contact can ultimately improve the fill factor of solar cells, reduce the packaging loss from cells to modules and module losses, and improve the photoelectric conversion efficiency and power output of photovoltaic modules. Since the manufacturing method and process window of n-type doped amorphous silicon or microcrystalline silicon thin films are superior to doped p-type amorphous silicon or microcrystalline silicon thin films, the technology of the present invention has a wider process window, which is beneficial to mass production Production process control and management are conducive to the promotion of large-scale industrialization and application of high-efficiency crystalline silicon thin-film silicon heterojunction solar cells, and are conducive to promoting the industrialization of high-efficiency crystalline silicon thin-film silicon heterojunction solar cells and the photovoltaic industry. Upgrades have a facilitative effect.

Description of drawings

FIG. 1 shows a schematic diagram of the basic structure of a double-sided light-receiving crystalline silicon/thin-film silicon heterojunction solar cell in the prior art.

Fig. 2 is a schematic diagram showing the basic structure of a photovoltaic module produced by using double-sided light-receiving crystalline silicon/thin-film silicon heterojunction solar cells in the prior art.

Fig. 3 is a schematic diagram showing the basic structure of the double-sided light-receiving crystalline silicon/thin-film silicon heterojunction solar cell of the present invention.

Fig. 4 shows the comparison of current-voltage curves between the technology of the present invention and the double-sided light-receiving crystalline silicon/thin-film silicon heterojunction of the prior art under AM1.5, 100mW/cm ² standard light conditions.

Fig. 5 shows the comparison of internal quantum efficiency (Internal Quantum Efficiency: IQE) curves between the technology of the utility model and the prior art double-sided light-receiving crystalline silicon/thin-film silicon heterojunction.

Fig. 6 is a schematic diagram showing the basic structure of a photovoltaic module made of double-sided light-receiving crystalline silicon/thin-film silicon heterojunction solar cells in the technology of the utility model.

Figure 7 shows the measured current-voltage characteristic curves of the double-sided light-receiving photovoltaic module under outdoor conditions, using a black shading material to cover the back, front shading and no shading.

Fig. 8 shows the comparison of the actual power generation of the double-sided light-receiving crystalline silicon/thin-film silicon heterojunction photovoltaic module of the present invention and the prior art on a certain day.

FIG. 9 shows a schematic diagram of the basic structure of a photovoltaic module fabricated using a high optical reflectivity backplane encapsulation material.

Component designation description

2 solar cells

21 window layer

211 Intrinsic amorphous silicon or microcrystalline silicon

212 n-type doped amorphous silicon or microcrystalline silicon

22 back field layer

221 Intrinsic amorphous silicon or microcrystalline silicon

222 p-type doped amorphous silicon or microcrystalline silicon

23 The first transparent conductive film

24 Second transparent conductive film

25 first electrode

26 Second electrode

3 sealing material

4 surface mount glass

5 sealing material

6 Backside packaging material

7 metal frame

8 Backside encapsulation material

Detailed ways

The implementation of the present utility model is described below through specific examples, and those skilled in the art can easily understand other advantages and effects of the present utility model from the content disclosed in this specification. The utility model can also be implemented or applied through other different specific implementation modes, and the details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the utility model.

Please refer to Figure 2 to Figure 9. It should be noted that the diagrams provided in this embodiment are only schematically illustrating the basic idea of the utility model, so that only the components related to the utility model are shown in the diagrams rather than the shape and size of the actual implementation Drawing, the shape and proportion of each component can be changed arbitrarily during its actual implementation, and the layout of the components may also be more complicated.

As shown in FIG. 3 , the present embodiment provides a crystalline silicon/thin-film silicon heterojunction solar cell 2 receiving light on both sides, and the solar cell 2 includes: an n-type silicon substrate having opposite first surfaces and second Two surfaces; the window layer 21 is formed on the first surface of the n-type silicon substrate, which includes intrinsic amorphous silicon or microcrystalline silicon 211 with a wide optical bandgap and n-type doped amorphous silicon or microcrystalline silicon Crystalline silicon 212; a back field layer 22 formed on the second surface of the n-type silicon substrate, which includes intrinsic amorphous silicon or microcrystalline silicon 221 and p-type doped amorphous silicon or microcrystalline silicon 222; The first transparent conductive film 23 is formed on the surface of the window layer 21; the second transparent conductive film 24 is formed on the surface of the back field layer 22; the first electrode 25 is formed on the first transparent conductive film 23; And the second electrode 26 is fabricated on the second transparent conductive film 24 .

As an example, the silicon substrate is n-type crystalline silicon.

As an example, the surface of the n-type silicon substrate is corroded by chemical reagents or etched by physical methods to make a regular concave-convex structure, that is, the surface is textured, so as to reduce the reflection loss of the surface of the n-type silicon substrate to sunlight, and the use of chemical reagents Or ozone aqueous solution, or use an ultraviolet light source to clean the surface to obtain a clean n-type silicon substrate surface.

As an example, an intrinsic amorphous silicon or microcrystalline silicon thin film 211 of the window layer 21 is deposited on the first surface of n-type crystalline silicon, and an intrinsic amorphous silicon or microcrystalline silicon thin film 212 of the back field layer 22 is deposited on the second surface, Form the crystalline silicon/thin-film silicon heterojunction interface, and use intrinsic amorphous silicon or microcrystalline silicon thin film to form good passivation on the dangling bonds on the surface of the n-type crystalline silicon substrate, so that the n-type crystalline silicon substrate The surface recombination rate is below 10 cm/s, and the thickness range of intrinsic amorphous silicon or microcrystalline silicon is 3-20 nm.

As an example, doping oxygen atoms into the intrinsic amorphous silicon or microcrystalline silicon thin film 211 of the deposition window layer 21 and the intrinsic amorphous silicon or microcrystalline silicon thin film 221 of the back field layer 22 to form a wide optical bandgap Silicon-based thin film, which suppresses the crystal epitaxial growth of amorphous silicon or microcrystalline silicon thin film on the surface of n-type silicon substrate, and obtains high optical transmittance and low-defect intrinsic layer at the same time, wherein the doping amount of oxygen atoms is 5×10 ¹⁹ ～5×10 ²⁰ cm ⁻³ .

As an example, an n-type doped amorphous silicon or microcrystalline silicon film 212 is deposited on the surface of the intrinsic amorphous silicon or microcrystalline silicon film 211 on the first surface of the n-type crystalline silicon substrate, and between the n-type substrate A built-in electric field is formed, and photogenerated carriers near the first surface of the n-type crystalline silicon substrate are collected through the action of the built-in electric field, wherein the thickness of the window layer ranges from 4 to 10 nm.

As an example, carbon atoms are doped into the n-type doped amorphous silicon or microcrystalline silicon film 212 to form an amorphous or microcrystalline silicon-carbon film, so as to reduce the n-type doped amorphous silicon or microcrystalline silicon film. Defect density, extended optical bandgap width, wherein the doping amount of carbon is 7×10 ¹⁹ to 2×10 ²⁰ cm ^-3 .

As an example, a p-type doped amorphous silicon or microcrystalline silicon film 222 is deposited on the surface of the intrinsic amorphous silicon or microcrystalline silicon film 221 on the second surface of the n-type crystalline silicon substrate, and the n-type substrate A built-in electric field is formed between them, and the photogenerated carriers near the second surface of the n-type crystalline silicon substrate are collected by the built-in electric field, wherein the p-type doped amorphous silicon or microcrystalline silicon thin film 222 has a thickness range of 4 ~20nm.

As an example, the first transparent conductive film 23 is deposited on the surface of the window layer 21, and the transparent conductive film 23 has good optical transmittance, high electrical conductivity, and a transparent conductive film or a thin laminated material with a suitable refractive index. To collect the carriers on the first surface and reduce the reflection loss of sunlight on the surface of the window layer, the first transparent conductive film 23 includes tin-doped indium oxide, aluminum-doped indium oxide, tungsten-doped indium oxide, titanium-doped indium oxide , cesium-doped indium oxide, aluminum-doped zinc oxide, gallium-doped zinc oxide, aluminum-gallium-doped zinc oxide, graphene, and a superposition combination of one or more thin film materials.

As an example, a second transparent conductive film 24 is deposited on the surface of the back field layer 22. The transparent conductive film 24 has a transparent conductive film or a thin stack material with good electrical conductivity and high work function, and is used to provide a current-carrying material for collecting the second surface. The second transparent conductive film 24 includes tin-doped indium oxide, aluminum-doped indium oxide, tungsten-doped indium oxide, titanium-doped indium oxide, cesium-doped indium oxide, aluminum-doped zinc oxide, gallium-doped zinc oxide, aluminum-gallium-doped indium oxide A superposition combination of one or more thin film materials in zinc and graphene.

The utility model also provides a photovoltaic module, which is formed by connecting a plurality of crystalline silicon/thin film silicon heterojunction solar cells 2 that receive light on both sides in series or in parallel by using metal interconnection wires or metal interconnection strips. The window layer 21 of the solar cell 2 faces toward the light-receiving surface of the photovoltaic module, and the back field layer 22 is arranged toward the back of the photovoltaic module, so that the window layer 21 of the solar cell 2 becomes the main light-receiving surface.

As an example, the encapsulation material on the front surface of the photovoltaic module is selected as tempered white glass or transparent resin material with high optical transmittance, low optical reflectance, and high load capacity, so as to ensure that the solar cells 2 encapsulated inside are provided with solar energy. Light irradiation, and provide loads generated by photovoltaic module transportation, installation, wind pressure, and snow accumulation.

As an example, the back packaging material of the photovoltaic module is selected as a material with high optical reflectivity, so that the double-sided light-receiving crystalline silicon/thin film silicon heterojunction solar cell 2 encapsulated inside receives the reflected light of the back packaging material Gain in photoelectric conversion efficiency and power generation.

As an example, the backside packaging material of the photovoltaic module is selected as a material with high optical transmittance, so that the double-sided light-receiving crystalline silicon/thin-film silicon heterojunction solar cell 2 encapsulated inside receives the reflected light from the backside environment And the scattered light obtains the gain of photoelectric conversion efficiency and power generation.

As an example, a metal frame is installed on the edge of the photovoltaic module and coated with high-strength sealing material to further improve the sealing and load capacity of the photovoltaic module.

The utility model also provides a method for manufacturing a double-sided crystalline silicon/thin film silicon heterojunction solar cell 2, which includes the steps of: providing an n-type crystalline silicon substrate, which has opposite first and second surfaces; Depositing a first intrinsic amorphous silicon or microcrystalline silicon film 211 on the first surface of the n-type silicon substrate, and doping oxygen atoms at the same time, so that in the first intrinsic amorphous silicon or microcrystalline silicon film Forming an amorphous or microcrystalline silicon oxygen or silicon carbon film; depositing n-type doped amorphous silicon or microcrystalline silicon 212 on the surface of the first intrinsic amorphous silicon or microcrystalline silicon film located on the first surface, and simultaneously Doping carbon atoms to form an amorphous or microcrystalline silicon carbon film in the n-type doped amorphous silicon or microcrystalline silicon film 212; depositing a second Intrinsic amorphous silicon or microcrystalline silicon film 221; deposit p-type doped amorphous silicon or microcrystalline silicon 222 on the surface of the second amorphous silicon or microcrystalline silicon film located on the second surface; A first transparent conductive film 23 is formed on the surface of the p-type doped amorphous silicon or microcrystalline silicon 212; a second transparent conductive film 24 is formed on the surface of the p-type doped amorphous silicon or microcrystalline silicon 222; A first electrode 25 is fabricated on a transparent conductive film 23 ; a second electrode 26 is fabricated on the second transparent conductive film 24 .

As an example, providing an n-type crystalline silicon substrate further includes the steps of texturing and cleaning the first surface and the second surface of the n-type silicon substrate.

As an example, the first intrinsic amorphous silicon or microcrystalline silicon film 211, the second intrinsic amorphous silicon or microcrystalline silicon film 221, n-type doped amorphous silicon or microcrystalline silicon 212, p-type The method of doping amorphous silicon or microcrystalline silicon 222 includes one of plasma enhanced vapor deposition method PE-CVD, metal thermal catalytic chemical vapor deposition method Cat-CVD, and hot wire chemical vapor deposition method Hot-wire CVD .

As an example, intrinsic amorphous silicon or microcrystalline silicon thin films 211 and 221 are deposited on the first surface and the second surface of the n-type crystalline silicon substrate, and oxygen atoms are doped at the same time, so that the first and second Intrinsic amorphous silicon or microcrystalline silicon thin films 211 and 221 are formed with amorphous or microcrystalline silicon oxygen thin films.

As an example, an n-type doped amorphous silicon or microcrystalline silicon film 212 is deposited on the surface of the first intrinsic amorphous silicon or microcrystalline silicon film 211 located on the first surface, and carbon atoms are doped at the same time, so as to An amorphous or microcrystalline silicon carbon film is formed in the n-type doped amorphous silicon or microcrystalline silicon film 212 .

As an example, a p-type doped amorphous silicon or microcrystalline silicon film 222 is deposited on the surface of the second intrinsic amorphous silicon or microcrystalline silicon film 221 located on the second surface.

The utility model discloses a basic structure and manufacturing method of a crystalline silicon/thin-film silicon heterojunction solar cell 2 and a photovoltaic module, referring to Fig. 3 and Fig. 6, aiming at the technical and process details in the manufacturing process of the cell and the module, including crystalline silicon Texture and cleaning of the surface, deposition of amorphous silicon or microcrystalline silicon film, deposition of transparent conductive film (hereinafter referred to as TCO film), formation of metal electrodes, conductive interconnection ribbons and production methods can have a variety of options, This patent does not make specific regulations and limitations. According to the specific needs of the thin film manufacturing process and solar cell structure, considering factors such as manufacturing process cost, equipment and even the technical preferences of the responsible personnel, it will not affect the effect of the battery and components, and will not deviate from this patent. The basic physical ideas and implementation effects involved in the patent, for example, crystalline silicon wafers can choose Czochralski single crystal (CZ) or cast quasi-single crystal silicon wafers, or even zone fusion (FZ) single crystal silicon wafers. The texturing of monocrystalline silicon wafers can be either alkaline solution plus additive etching or plasma etching. For cleaning, you can choose conventional RCA cleaning, or you can choose to use ozone aqueous solution, or even directly irradiate with ultraviolet light, etc. Amorphous silicon or microcrystalline silicon film deposition can choose plasma enhanced chemical vapor deposition (hereinafter referred to as PE-CVD), microwave induced chemical vapor deposition (hereinafter referred to as MW-CVD), metal thermal catalytic chemical vapor deposition (hereinafter referred to as Cat-CVD), Hot wire chemical vapor deposition (hereinafter referred to as Hot-wire CVD), etc. TCO film deposition can adopt various methods and equipment such as plasma reactive deposition (RPD) or magnetron sputtering (PVD), electron beam coating, etc. Metal electrodes can use conventional screen printing, or metal wire direct composite technology, etc. Except for the backplane encapsulation material that needs to be selected according to the characteristics of the double-sided Shouguang solar cell 2, other sealing materials and processes are the same as those selected in conventional module production, and are not restricted by this patent. There is technology, which does not affect the specific implementation of this patent and the effect on batteries and components.

Example 1

In this embodiment, PE-CVD amorphous silicon film deposition equipment and RPD transparent conductive film are mainly used to produce crystalline silicon/thin film silicon heterojunction solar cells 2, and the backplane packaging material is glass to produce double-sided light-receiving photovoltaic modules for illustration.

Please refer to FIG. 3 and FIG. 6 , which show the basic structure of the solar cell 2 and the photovoltaic module fabricated in this embodiment.

The n-type monocrystalline silicon wafer made by the CZ method is selected as the basic raw material of the solar cell 2. The resistivity of the silicon wafer is between 0.1 and 20Ωcm, and the thickness is between 100 and 200 microns. The thickness mainly depends on the load capacity of the equipment. The ability to maintain silicon wafers without damage and not affect the yield rate of the battery.

First, the surface of the silicon wafer is etched to remove the surface damage caused in the process of making the silicon wafer. After cleaning with pure water, potassium hydroxide or sodium hydroxide aqueous solution is used to add texture additives such as surfactants to the silicon wafer. Carry out texturing treatment to form a uniform "pyramid" textured structure on the surface of the silicon wafer. The size of the pyramid is based on the bottom edge of the tetrahedron, which is between 2 and 15 microns. The size of the pyramid is based on the characteristics of the subsequent thin film deposition equipment And the performance of the electrode fabrication equipment is determined.

After the textured monocrystalline silicon wafer is cleaned by RCA1 and RCA2, the silicon oxide layer on the surface is removed by hydrofluoric acid aqueous solution, rinsed with sufficient pure water, and then introduced into the amorphous silicon thin film deposition equipment.

Amorphous silicon thin film deposition equipment chooses radio frequency or very high frequency plasma enhanced chemical vapor deposition equipment, the plasma frequency is 13.56MHz, that is, RF PE-CVD, n-type and p-type doped amorphous silicon or microcrystalline silicon thin film deposition VHF-CVD equipment with a frequency of 27.12MHZ or 40MHz can also be selected. The PE-CVD equipment has four separate process chambers, each chamber is separated by a vacuum valve, and the pallet is transported through the automatic equipment of the transmission mechanism. Normally, the vacuum pump is kept in working condition to keep all process chambers in a vacuum state.

The single crystal silicon wafer is placed on the tray, and the tray is transported to the first process chamber, where the second intrinsic amorphous silicon thin film layer 221 of the back field layer 22 is firstly deposited. After the silicon wafer is heated to the set temperature, the process gas is introduced to start film deposition, and the surface temperature of the silicon wafer is between 150 and 200 degrees. The process gas is a mixed gas of high-purity SiH ₄ , H ₂ and CO ₂ . The goal of setting the deposition conditions of the amorphous silicon film is to increase the disorder degree of the intrinsic amorphous silicon layer as much as possible, so that the amorphous silicon film is opposite to the crystalline silicon surface. It has a good passivation effect, and the purpose of introducing _CO2 gas is to make the intrinsic amorphous silicon film doped with a small amount of oxygen atoms to form amorphous silicon oxygen, and at the same time inhibit the formation of crystal structure of amorphous silicon on the surface of crystalline silicon. The thickness of the second intrinsic amorphous silicon thin film layer 221 is between 3 and 10 nanometers, the optical bandgap width is between 1.6 and 1.8 eV, and the hydrogen content in the film is between 8 and 20%.

The tray is transported to the second process chamber to deposit the p-type amorphous silicon thin film 222 of the back field layer 22 . Similarly, after the silicon wafer is heated to reach the set temperature, the process gas is introduced to start the film deposition. The surface temperature of the silicon wafer is between 150 and 250 degrees, and the process gas is a mixed gas of high-purity SiH ₄ , H ₂ and B ₂ H ₆ . The goal of setting the deposition conditions of the amorphous silicon film is to make the p-type amorphous silicon layer The structure factor is characteristic of the structure of microcrystalline silicon. The thickness of the p-type amorphous silicon film layer 222 is between 4 and 20 nanometers, the optical bandgap width is around 1.6eV, and the hydrogen content in the film is between 8 and 20%.

The tray is removed from the second process chamber, the silicon wafer is turned over so that the side where the amorphous silicon film has been deposited is facing down, and then the tray is transferred to the third process chamber for the intrinsic amorphous silicon film layer 211 of the window layer 21. deposition. The process conditions and film characteristics of the intrinsic amorphous silicon thin film 211 are the same as those of the intrinsic amorphous silicon thin film layer 221 of the back field layer 22 of the first process chamber.

The tray is transferred to the fourth process chamber to deposit the n-type amorphous silicon thin film layer 212 of the window layer 21 . Similarly, after the silicon wafer is heated to reach the set temperature, the process gas is introduced to start the film deposition. The surface temperature of the silicon wafer is between 150 and 250 degrees, and the process gas is a mixed gas of high-purity SiH ₄ , H ₂ , PH ₃ and CO ₂ . The goal of setting the deposition conditions of the amorphous silicon film is to make n-type amorphous silicon The layer structure factor has the characteristics of the microcrystalline silicon structure. The purpose of introducing _CO2 gas is to dope carbon atoms in the n-type amorphous silicon film to form a silicon-carbon film, widen the band gap of the n-type window layer 212, and reduce the thickness of the film. defect density within. The thickness of the n-type amorphous silicon carbon film is between 4 and 10 nanometers, the width of the optical band gap is around 1.6 to 2.4eV, and the hydrogen content in the film is between 8 and 15%.

Transfer the silicon wafer with amorphous silicon film stack deposited on both sides to the RPD equipment, and deposit TCO film on both sides of the silicon wafer.

Place the silicon wafer on a tray with an opening, with the p-type back field layer 22 facing down, heat the silicon wafer to reach the set temperature, and then inject process gas to start film deposition. The surface temperature of the silicon wafer is between 80-200 degrees During the process, the process gas is a mixed gas of argon and oxygen, and the target material is tungsten-doped indium oxide (IWO). The effective thickness of the film is set according to the application scene of the photovoltaic module. In principle, it is adjusted between 40 and 120nm, and the surface resistivity is between Between 20-100Ω/square.

After the deposition of the p-type back field layer 22 is completed, the silicon wafer is turned over, and the TCO film is deposited on the n-type window layer 21. The process conditions are basically the same as above. The thickness of the TCO film is about 80nm, and the surface resistivity is 30-80Ω/square. The average optical transmittance of the light wavelength between 350-1200nm is over 90%.

The metal electrodes are made respectively on the back field layer 22 and the window layer 21 by screen printing, and the raw material is low-temperature cured silver paste. Firstly, fine grid lines and main grid lines are printed on the back field layer 22, and after low-temperature drying, surface electrodes are printed on the window layer 21, and then high-temperature curing is performed after low-temperature drying. The low-temperature drying temperature is between 100 and 160 degrees, and the high-temperature curing temperature varies greatly due to the different silver paste materials used, generally between 180 and 250 degrees.

After the above process, the production of double-sided light-receiving crystalline silicon/thin-film silicon heterojunction solar cell 2 is completed. After testing and sorting, the photovoltaic module is produced. Its basic structure is shown in Figure 3.

Fig. 4 shows the double-sided light-receiving crystalline silicon/thin film silicon heterojunction solar cell ² of the utility model technology (curve a) and the prior art (curve b) at AM1.5, the electric current of 100mW/cm under the standard illumination condition- Comparing the voltage curves, it can be clearly seen that the current, voltage and fill factor of the former are more or less increased, and the final effect is to increase the conversion efficiency of the battery by more than 0.5%.

Fig. 5 shows the internal quantum efficiency (Internal Quantum Efficiency: IQE) curve comparison of the utility model technology (curve a) and the prior art (curve b) double-sided light-receiving crystalline silicon/thin-film silicon heterojunction solar cell 2, which can be clearly It can be seen that the spectral response of the former in the short wavelength and visible light region is significantly improved, which is consistent with the results shown in Figure 4.

Arrange the cells after the test binning according to the direction that the n-type window layer 21 faces upwards and the p-type back field layer 22 faces downwards, and connect the cells in series by using metal ribbons, that is, connect the front electrode of one cell to the back side of the adjacent cell The electrodes are connected, and so on to form battery substrings. The number of batteries in each substring is determined according to the battery current, voltage and related standards. Multiple battery substrings are connected in series or in parallel to form a regular square matrix, and lead out electrode.

In the order from top to bottom, stack the surface packaging glass 4, sealing material 3, battery array 2, sealing material 5, and back packaging material 6 together, put them into a vacuum laminator with a heating environment and heat until the sealing material The required temperature, the use of vacuum and mechanical load to apply a certain pressure, so that the packaging glass and the battery sheet are tightly combined. The back packaging material of the photovoltaic module is selected as a material with high optical transmittance, so that the double-sided light-receiving crystalline silicon/thin film silicon heterojunction solar cell 2 encapsulated inside can receive the reflected light and scattered light of the back environment To obtain the gain of photoelectric conversion efficiency and power generation, the optical transmittance of the back packaging material is above 85%

Lead the wires from the wiring holes on the back or the edge, apply sealant on the edge and install the metal frame 7 to make a photovoltaic module that receives light on both sides. Its basic structure is shown in Figure 6.

Figure 7 shows the current-voltage curves of the photovoltaic module under outdoor conditions, using a black shading plate to cover the back (curve a), front cover (curve b) and no cover (curve c). It can be clearly seen that in Under the condition that there is no sunlight on the front side, the back side of the photovoltaic module also has current-voltage output characteristics, indicating that the back side receives the reflected light from the ground and the scattered light from the surrounding environment to generate power generation output. Under the condition that both the front and the back are irradiated with light at the same time, the total power generation output of the photovoltaic module is almost the superposition of the power generation output of the front side and the power generation output of the back side.

Figure 8 shows the comparison of the actual power generation of the double-sided light-receiving crystalline silicon/thin-film silicon heterojunction photovoltaic module of the present invention (curve a) and the prior art (curve b). It can be clearly seen that the actual power generation of the former on a certain day has increased significantly.

It can be seen from the above process that the photovoltaic module uses an n-type amorphous silicon thin film with a wide optical band gap and low defect density as the window layer 21, which can effectively reduce the absorption of sunlight by the window layer 21 and increase the current of the solar cell 2. In this way, the conversion efficiency and output power of the photovoltaic module are improved. At the same time, the back of the photovoltaic module receives the reflected light and scattered light on the back to generate current and voltage output, which is superimposed on the front current and voltage output, further improving the power generation output of the photovoltaic module. It shows the superiority of double-sided light-receiving solar cells 2 and photovoltaic modules in terms of power generation gain.

Above, the PE-CVD equipment has four independent process chambers, and the four layers of amorphous silicon films are deposited in four different process chambers respectively. The advantage of this structure is that it can increase the process rate and avoid the interference between different films. Cross effects, especially between the p-type and n-type doped layers and the contamination of the doped layer to the intrinsic amorphous silicon layer. However, according to equipment conditions and production requirements, the number of process chambers can also be reduced. For example, the intrinsic amorphous silicon films of the window layer 21 and the back field layer 22 can be deposited in the same chamber, and even n-type amorphous silicon films can be deposited in the same chamber. It can also share the same process chamber with intrinsic amorphous silicon, which does not affect the implementation effect of the content of this patent.

Similarly, the TCO film is prepared by RPD equipment. Under the same conditions, magnetron sputtering equipment can also be used, or even a combination of magnetron sputtering and RPD. These changes will not affect the implementation effect of the revised patent.

Similarly, in addition to screen printing, metal electrodes can also be electroplated or directly compounded with metal wires. These changes will not affect the performance of batteries and components, and will not deviate from the implementation effect of this patent. On the contrary, this patent is more receptive to the introduction of related new technologies to improve the performance of batteries and components outside of the internal structure of batteries.

Example 2

The difference between this embodiment and the first embodiment lies in that the amorphous silicon thin film is produced by using metal thermal catalytic chemical vapor deposition (Cat-CVD) equipment instead of PE-CVD equipment. Compared with PE-CVD, Cat-CVD has low deposition rate, good process stability and repeatability; the structure factor of amorphous silicon film is closer to microcrystalline silicon structure, which can obtain higher open circuit voltage and fill factor, thus Get higher conversion efficiency. Since the principles and structures of Hot-wire CVD and Cat-CVD are basically the same, this embodiment actually includes two methods of Cat-CVD and Hot-wire CVD.

The selection of silicon wafers in this embodiment, the texturing and cleaning parts are the same as those in Embodiment 1 and will not be repeated.

Cat-CVD has four independent process chambers, which are separated by vacuum valves, and are used to deposit window layer 211 intrinsic amorphous silicon, window layer 212n-type amorphous silicon, and back field layer 221 intrinsic amorphous Silicon and back field layer 222p amorphous silicon. Under normal conditions, the vacuum pump is kept in working condition to keep all the process chambers in a vacuum state, and the pallets are transported between each chamber through the transmission mechanism.

Place the textured and cleaned silicon wafers in the Cat-CVD tray and introduce them into the pretreatment chamber (L-chamber) of the Cat-CVD equipment. The mixed gas turns on the heating device in the chamber to heat the silicon wafer. The background vacuum of the pretreatment chamber is below 0.1Pa, the pressure in the chamber is maintained at 0.1Pa after introducing hydrogen, the heating temperature of the silicon wafer is between 120-250°C, and the heating time is about 240 seconds.

After the heat treatment, the tray is transferred to the first process chamber for depositing the first intrinsic amorphous silicon thin film 211 on the first surface. Introduce the mixed gas of SiH ₄ and H ₂ into the process chamber. After reaching the set pressure, the hot wire is energized and heated. The temperature of the hot wire not only ensures the effective decomposition of the process gas to form the deposition of amorphous silicon film, but its radiant heat has great impact on the silicon wafer. It also has a heating function, so when the set temperature is reached, the deposition of amorphous silicon film will start naturally. The surface temperature of the hot wire is between 1500 and 2000 degrees, and the surface temperature of the silicon wafer is between 150 and 200 degrees. The goal of setting the filament temperature is to make the structure factor of intrinsic amorphous silicon have the characteristics of microcrystalline silicon structure. The effective thickness of the intrinsic amorphous silicon film is between 3 and 20 nanometers, the optical band gap width is between 1.6 and 1.8 eV, and the hydrogen content in the film is between 10 and 20%.

The tray is transferred to the second process chamber for deposition of the window layer 212 n-type amorphous silicon film. Similarly, the mixed gas of SiH ₄ , H ₂ and PH ₃ is fed into the process chamber, and when the set pressure is reached, the heating wire is energized and heated. The surface temperature of the hot wire is between 1800 and 2400 degrees, and the surface temperature of the silicon wafer is between 180 and 250 degrees. The goal of setting the deposition conditions is to make the structure factor of the n-type amorphous silicon layer have the characteristics of the microcrystalline silicon structure. The effective thickness of the amorphous silicon film is between 4 and 10 nanometers, the optical bandgap width is around 1.6 to 2.4eV, and the hydrogen content in the film is between 8 and 20%.

The tray is removed from the second process chamber, the silicon wafer is turned over so that the side on which the amorphous silicon film has been deposited is facing down, and then the tray is transferred to the third process chamber to perform the second intrinsic amorphous silicon film 221 on the second surface. deposition. The process conditions and film characteristics of the intrinsic amorphous silicon film are the same as those of the first process chamber.

Transfer the tray to the fourth process chamber for back field layer 222p-type amorphous silicon thin film deposition. Similarly, the mixed gas of SiH ₄ , H ₂ and B ₂ H ₆ is fed into the process chamber, and when the set pressure is reached, the heating wire is heated by electricity. The surface temperature of the hot wire is between 1800 and 2400 degrees, and the surface temperature of the silicon wafer is between 150 and 250 degrees. The goal of setting the deposition conditions is to make the structure factor of the p-type amorphous silicon layer have the characteristics of the microcrystalline silicon structure. The effective thickness of the amorphous silicon film is between 4 and 20 nanometers, the optical bandgap width is around 1.6eV, and the hydrogen content in the film is between 8 and 15%.

Transfer the silicon wafer with laminated amorphous silicon thin film deposited on both sides to the TCO thin film production equipment, and deposit the TCO thin film on both sides of the silicon wafer. The deposition method and fabrication method of the TCO thin film are the same as those in Embodiment 1 and will not be repeated.

Example 3

As shown in FIG. 9 , the difference between this embodiment and the first embodiment is that a backplane encapsulation material 8 with high optical reflectivity is used instead of a backplane glass to make a photovoltaic module. Compared with glass with high optical transmittance on both sides, the back sheet material reflects the sunlight that passes through the solar cell 2 and is incident between the solar cells 2 to the back of the solar cell 2, so that the back of the solar cell 2 generates electricity The output is superimposed on the front power generation output to increase the power generation of photovoltaic modules. The photovoltaic module is more suitable for occasions such as roofs with poor back reflection conditions.

Arrange the cells after the test binning according to the direction that the n-type window layer 21 faces upwards and the p-type back field layer 22 faces downwards, connect the cells in series by using metal ribbons, and connect the front electrode of one cell to the back electrode of an adjacent cell , and so on to form battery substrings. The number of batteries in each substring is determined according to the current, voltage and related standards of the battery. Multiple battery substrings are connected in series or in parallel to form a regular square array. For the safety of photovoltaic modules, a diode or other protection components are connected in antiparallel to both ends of each substring, and electrodes are drawn out.

In order from top to bottom, stack the packaging glass, sealing material, battery array, sealing material, and high-reflectivity backsheet material together, and put them into a vacuum laminator with a heating environment to heat to the temperature required for the sealing material , using vacuum and mechanical load to apply a certain pressure, so that the packaging glass and the battery sheet are tightly combined.

Lead wires from the wiring holes on the back or edge, apply sealant on the edge and install a metal frame to make a photovoltaic module that receives light on both sides. Its basic structure is shown in Figure 9.

Therefore, the utility model effectively overcomes various shortcomings in the prior art and has high industrial application value.

The above-mentioned embodiments only illustrate the principles and effects of the present utility model, but are not intended to limit the present utility model. Anyone familiar with this technology can modify or change the above-mentioned embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or changes made by those with ordinary knowledge in the technical field without departing from the spirit and technical ideas disclosed in the utility model should still be covered by the claims of the utility model.

Claims (13)

1. A double-sided crystalline silicon/thin film silicon heterojunction solar cell, characterized in that the solar cell comprises: an n-type silicon substrate having opposite first and second surfaces; a window layer formed on the first surface of the n-type silicon substrate, which includes intrinsic amorphous silicon or microcrystalline silicon with a wide optical bandgap and n-type doped amorphous silicon or microcrystalline silicon; a back field layer formed on the second surface of the n-type silicon substrate, which includes intrinsic amorphous silicon or microcrystalline silicon and p-type doped amorphous silicon or microcrystalline silicon; a first transparent conductive film formed on the surface of the window layer; a second transparent conductive film formed on the surface of the back field layer; a first electrode fabricated on the first transparent conductive film; The second electrode is fabricated on the second transparent conductive film. 2. The crystalline silicon/thin film silicon heterojunction solar cell receiving light on both sides according to claim 1, characterized in that: the silicon substrate is n-type crystalline silicon. 3. The crystalline silicon/thin film silicon heterojunction solar cell receiving light on both sides according to claim 1, characterized in that: the intrinsic amorphous silicon is deposited on the first and second surfaces of the n-type crystalline silicon substrate respectively Silicon or microcrystalline silicon thin film forms a heterojunction interface of crystalline silicon/thin film silicon, and uses intrinsic amorphous silicon or microcrystalline silicon to form a good passivation effect on the dangling bonds on the surface of the n-type crystalline silicon substrate, so that The surface recombination rate of the n-type silicon substrate is below 10 cm/s, wherein the thickness range of intrinsic amorphous silicon or microcrystalline silicon is 3-20 nm. 4. The crystalline silicon/thin-film silicon heterojunction solar cell receiving light on both sides according to claim 1, characterized in that: doping oxygen atoms into the intrinsic amorphous silicon or microcrystalline silicon to form a silicon-oxygen thin film , inhibit the crystal epitaxial growth of amorphous silicon or microcrystalline silicon film on the surface of n-type silicon substrate, and obtain high optical transmittance and low defect intrinsic layer at the same time, wherein the doping amount of oxygen atoms is 5×10 ¹⁹ ~ 5×10 ²⁰ cm ^-3 . 5. The crystalline silicon/thin film silicon heterojunction solar cell receiving light on both sides according to claim 1, characterized in that: the intrinsic amorphous silicon or microcrystalline silicon on the first surface of the n-type crystalline silicon substrate An n-type doped amorphous silicon or microcrystalline silicon film is deposited on the surface of the film, and a built-in electric field is formed between the n-type substrate, and the light generated near the first surface of the n-type crystalline silicon substrate is collected by the built-in electric field. flow, wherein the thickness of the window layer ranges from 4 to 10 nm. 6. The crystalline silicon/thin film silicon heterojunction solar cell receiving light on both sides according to claim 1, characterized in that: doping carbon atoms into the n-type amorphous silicon or microcrystalline silicon thin film to form an amorphous Or a microcrystalline silicon-carbon film to reduce the defect density of n-type amorphous silicon or microcrystalline silicon film and expand the optical bandgap width, wherein the doping amount of carbon is 7×10 ¹⁹ to 2×10 ²⁰ cm ^-3 . 7. The crystalline silicon/thin film silicon heterojunction solar cell receiving light on both sides according to claim 1, characterized in that: the intrinsic amorphous silicon or microcrystalline silicon on the second surface of the n-type crystalline silicon substrate A p-type doped amorphous silicon or microcrystalline silicon film is deposited on the surface of the film, and a built-in electric field is formed between the n-type substrate and the photo-generated load near the second surface of the n-type crystalline silicon substrate is collected by the built-in electric field. flow, wherein the thickness of the back field layer ranges from 4 to 20 nm. 8. The crystalline silicon/thin film silicon heterojunction solar cell receiving light on both sides according to claim 1, characterized in that: a first transparent conductive film is deposited on the surface of the window layer on the first surface of the n-type crystalline silicon substrate, the The transparent conductive film has good optical transmittance, high electrical conductivity, and a suitable refractive index transparent conductive film or thin laminated material, which is used to collect the carriers on the first surface and reduce sunlight on the surface of the window layer. reflection loss, the first transparent conductive film includes tin-doped indium oxide, aluminum-doped indium oxide, tungsten-doped indium oxide, titanium-doped indium oxide, cesium-doped indium oxide, aluminum-doped zinc oxide, gallium-doped zinc oxide, aluminum-gallium-doped A combination of one or more thin film materials in zinc oxide and graphene. 9. The crystalline silicon/thin film silicon heterojunction solar cell receiving light on both sides according to claim 1, characterized in that: a second transparent conductive film is deposited on the surface of the back field layer on the second surface of the n-type crystalline silicon substrate, The transparent conductive film has good electrical conductivity and high work function transparent conductive film or thin lamination material, which is used to provide carriers for collecting the second surface. The second transparent conductive film includes tin-doped indium oxide, aluminum-doped indium oxide Indium, tungsten-doped indium oxide, titanium-doped indium oxide, cesium-doped indium oxide, aluminum-doped zinc oxide, gallium-doped zinc oxide, aluminum-gallium-doped zinc oxide, and graphene are superimposed combinations of one or more thin film materials. 10. A photovoltaic module, characterized in that: the photovoltaic module uses metal interconnection wires or metal interconnection strips to connect a plurality of double-sided light-receiving crystalline silicon/thin film silicon heterojunctions according to any one of claims 1 to 9 The solar cells are connected in series or in parallel, the window layers of the solar cells face the direction of the light-receiving surface of the photovoltaic module, and the back field layers are arranged toward the back of the photovoltaic module, so that the window layer of the solar cell becomes the main light-receiving surface. 11. The photovoltaic module according to claim 10, characterized in that: the front surface packaging material of the photovoltaic module is selected as tempered white glass or transparent resin material with high optical transmittance, low optical reflectivity and high load capacity, It is used to ensure the solar radiation provided to the solar cells packaged inside, and to provide loads generated by the transportation, installation, wind pressure, and snow accumulation of photovoltaic modules. 12. The photovoltaic module according to claim 10, characterized in that: the back packaging material of the photovoltaic module is selected as a material with high optical reflectivity, so that the double-sided light-receiving crystalline silicon/thin film silicon encapsulated inside is different The mass junction solar cell receives the reflected light of the back packaging material to obtain the gain of photoelectric conversion efficiency and power generation. 13. The photovoltaic module according to claim 10, characterized in that: the back packaging material of the photovoltaic module is selected as a material with high optical transmittance, so that the double-sided light-receiving crystalline silicon/thin film silicon encapsulated inside Heterojunction solar cells receive reflected light and scattered light from the back environment to gain photoelectric conversion efficiency and power generation.