阅读说明：本技术 一种高效率双面受光柔性硅异质结太阳电池的制备方法 (Preparation method of high-efficiency double-sided light-receiving flexible silicon heterojunction solar cell ) 是由 张丽平 姚宇波 刘正新 孟凡英 石建华 刘文柱 于 2020-05-29 设计创作，主要内容包括：本发明涉及一种高效率双面受光柔性硅异质结太阳电池的制备方法,包括：提供一经过制绒清洗得到的表面清洁的柔性晶体硅衬底；在柔性衬底的相对两侧分别沉积非晶硅薄膜钝化层；在非晶硅薄膜钝化层上分别沉积第一TCO薄膜形成第一受光面和具有增强的红外波段光谱响应的背反射复合薄膜形成第二受光面,其中,背反射复合薄膜由第二TCO薄膜和金属纳米颗粒构成；在第一TCO薄膜和背反射复合薄膜上分别形成金属栅极。本发明利用第二受光面中不同分布的金属纳米颗粒的表面等离子体激元效应增强红外波段的光谱响应,克服柔性硅异质结太阳电池由于基底厚度不足引起的红外区域光谱响应差的缺点,有效提升柔性硅异质结太阳电池的短路电流和转换效率。(The invention relates to a preparation method of a high-efficiency double-sided light-receiving flexible silicon heterojunction solar cell, which comprises the following steps: providing a flexible crystalline silicon substrate with a clean surface obtained through texturing and cleaning; respectively depositing amorphous silicon thin film passivation layers on two opposite sides of the flexible substrate; respectively depositing a first TCO film on the amorphous silicon film passivation layer to form a first light receiving surface and a back reflection composite film with enhanced infrared band spectral response to form a second light receiving surface, wherein the back reflection composite film is composed of a second TCO film and metal nano-particles; and respectively forming metal gates on the first TCO film and the back reflection composite film. According to the invention, the surface plasmon effect of the metal nanoparticles distributed in the second light receiving surface in different ways is utilized to enhance the spectral response of the infrared band, so that the defect of poor spectral response of the infrared region of the flexible silicon heterojunction solar cell caused by insufficient substrate thickness is overcome, and the short-circuit current and the conversion efficiency of the flexible silicon heterojunction solar cell are effectively improved.)

1. A preparation method of a high-efficiency double-sided light-receiving flexible silicon heterojunction solar cell is characterized by comprising the following steps:

s1, providing a flexible crystalline silicon substrate with a clean surface obtained through texturing and cleaning;

s2, respectively depositing amorphous silicon thin film passivation layers on two opposite sides of the flexible substrate;

s3, respectively depositing a first TCO film on the amorphous silicon film passivation layer to form a first light receiving surface and a back reflection composite film with enhanced infrared band spectral response to form a second light receiving surface, wherein the back reflection composite film is composed of a second TCO film and metal nano-particles;

and S4, forming metal gates on the first TCO film and the back reflection composite film respectively.

2. The method of claim 1, wherein the metal nanoparticles are gold, silver, indium, and/or aluminum.

3. The method according to claim 1, wherein the metal nanoparticles have a particle size of 100 to 300 nm.

4. The method of claim 1, wherein the back reflection composite film is prepared by at least one of thermal evaporation, electron beam evaporation, physical vapor deposition, magnetron sputtering, and reactive plasma deposition.

5. The method of claim 1, wherein the back reflection composite film is a sandwich structure or a periodic alternate deposition stack structure.

6. The preparation method of claim 1, wherein the preparation process of the back reflection composite film comprises the following steps: preparing a first TCO film on the amorphous silicon film passivation layer; preparing a metal film on the first TCO film; annealing the metal film to form metal nano particles; and preparing a second sub TCO film on the metal nano-particles.

7. The production method according to claim 6, wherein the metal thin film is annealed at a low temperature of 200 ℃ or less to form the metal nanoparticles.

8. The preparation method according to claim 6, wherein different shape patterns are deposited on the metal film by means of mask or photolithography in the process of preparing the metal film, and the coverage ratio of the metal film to the whole area of the battery is between 5% and 98%.

9. The preparation method according to claim 1, wherein the step S2 specifically comprises: preparing a first intrinsic amorphous silicon film and an n-type doped amorphous silicon film on a first surface of the flexible substrate, and preparing a second intrinsic amorphous silicon film and a p-type doped amorphous silicon film on a second surface of the flexible substrate, which is opposite to the first surface.

10. The method according to claim 9, wherein the step S3 specifically comprises: and preparing a first TCO film on the n-type doped amorphous silicon film, and preparing a back reflection composite film on the p-type doped amorphous silicon film.

Technical Field

The invention relates to solar cell manufacturing, in particular to a preparation method of a high-efficiency double-sided light-receiving flexible silicon heterojunction solar cell.

Background

Energy is a national incentive to live and develop. In the era of increasingly exhausted fossil energy and prominent environmental problems, the development of novel alternative energy sources can provide powerful guarantee for the sustainable development of national economy. Solar energy can be stably and continuously output, and is more competitive in clean energy. At present, crystalline silicon (c-Si) components in various configurations account for more than 90% of market share, and efficient components have absolute advantages in photovoltaic system installation from the aspects of power generation and cost saving. The high-efficiency crystalline silicon solar cell is the basis for obtaining high-efficiency components, and the development of the high-efficiency Silicon Heterojunction (SHJ) solar cell can obtain the components with higher efficiency. Meanwhile, in order to further expand the photovoltaic packaging capacity and reduce the cost, people pay attention to the thinning trend of the crystalline silicon substrate. In addition, after the crystalline silicon serving as the absorption layer is thinned, the SHJ solar cell has flexible characteristics, and the manufactured module also has flexible characteristics and can be arranged on a surface with curvature to realize power output, so that the flexible module has wider application while the cost is reduced.

However, from numerical simulations and actual device performance outputs it can be seen that: the I-V parameter of the SHJ solar cell changes along with the thinning of the silicon wafer, wherein the open-circuit voltage and the filling factor increase along with the thinning of the crystalline silicon substrate, and the short-circuit current is reduced due to the reduction of the number of photo-generated carriers caused by the thinning of the substrate. Therefore, the thinner the crystalline silicon substrate is, the higher the loss of short-circuit current is, and the more the conversion efficiency of the cell is reduced.

Disclosure of Invention

In order to solve the problem that in the prior art, in order to reduce the cost and reduce the short-circuit current and the conversion efficiency of the silicon heterojunction solar cell caused by thinning the crystalline silicon substrate, the invention provides a preparation method of a high-efficiency double-sided light-receiving flexible silicon heterojunction solar cell.

The preparation method of the high-efficiency double-sided light-receiving flexible silicon heterojunction solar cell comprises the following steps: s1, providing a flexible crystalline silicon substrate with a clean surface obtained through texturing and cleaning; s2, respectively depositing amorphous silicon film passivation layers on two opposite sides of the flexible crystalline silicon substrate; s3, depositing a first TCO (transparent conductive oxide) film on the amorphous silicon film passivation layer to form a first light receiving surface and depositing a back reflection composite film with enhanced infrared band spectral response to form a second light receiving surface, wherein the back reflection composite film is composed of a second TCO film and metal nano-particles; and S4, forming metal gates on the first TCO film and the back reflection composite film respectively.

According to the invention, the surface plasmon effect of the metal nanoparticles distributed in the second light receiving surface in different ways is utilized to enhance the spectral response of the infrared band, so that the defect of poor spectral response of the infrared region of the flexible silicon heterojunction solar cell caused by insufficient substrate thickness is overcome, and the short-circuit current and the conversion efficiency of the flexible silicon heterojunction solar cell are effectively improved. The back reflection composite film has the light trapping function and the capability of efficiently reflecting and efficiently collecting carriers, and improves the infrared response and absorption of the flexible silicon heterojunction solar cell through efficient light trapping. The back reflection composite film can be tested and characterized by an elliptical polarization spectrometer, and the component proportion of the oxide and the metal nano particles and the refractive index of the composite film are fitted and calculated through an equivalent medium theory. The reflection mechanism of the back reflection composite film comprises a plasmon near field enhancement effect and a re-reflection principle of multiple scattered light. The back reflection composite films with different shapes can reduce the blockage of the back light absorption of the solar cell and adjust the short circuit current of the solar cell.

Preferably, the TCO film is an ITO, IWO, IGO, and/or IOH film. It should be understood that the TCO film may also be other oxide materials that may be conductive. More preferably, the TCO film is a transparent conductive oxide film containing an indium group. In preferred embodiments, the TCO film includes indium tin oxide, indium tungsten oxide, and/or indium gallium oxide, etc.

Preferably, the metal nanoparticles are gold, silver, indium and/or aluminum. It should be understood that the metal nanoparticles may also be other metal particles capable of cooperating with the TCO to enhance the spectral response in the infrared band.

Preferably, the particle size of the metal nanoparticles is 100 to 300 nm. More preferably, the metal nanoparticles have a particle size of 100 to 250nm, thereby more effectively collecting and trapping incident light.

Preferably, the back reflection composite film is prepared by at least one of thermal evaporation, electron beam evaporation, physical vapor deposition, magnetron sputtering, and Reactive Plasma Deposition (RPD).

Preferably, the back reflection composite film is a sandwich structure or a periodic alternate deposition stack structure.

Preferably, the preparation process of the back reflection composite film comprises the following steps: preparing a first TCO film on the amorphous silicon film passivation layer; preparing a metal film on the first TCO film; annealing the metal film to form metal nano particles; and preparing a second sub TCO film on the metal nano-particles.

Preferably, the metal thin film is annealed at a low temperature of 200 ℃ or less to form metal nanoparticles. In a preferred embodiment, the metal film has a temperature of 150 ℃ to 200 ℃ N₂、H₂Or annealing in Ar for 60-90 minutes to form the metal nano-particles.

Preferably, in the process of preparing the metal film, different shape patterns are deposited on the metal film by means of a mask plate or photoetching, and the coverage ratio of the metal film to the whole area of the battery is between 5% and 98%.

Preferably, the step S1 is specifically: a flexible crystalline silicon substrate is provided, and after anisotropic etching of the substrate with an alkali solution (e.g., KOH, NaOH, or the like), surface texturing is performed, followed by cleaning (e.g., cleaning with RCA1 and RCA2 solutions or an oxidation method).

Preferably, the step S2 is specifically: preparing a first intrinsic amorphous silicon film and an n-type doped amorphous silicon film on a first surface of the flexible substrate, and preparing a second intrinsic amorphous silicon film and a p-type doped amorphous silicon film on a second surface of the flexible substrate, which is opposite to the first surface.

Preferably, the step S3 is specifically: and preparing a first TCO film on the n-type doped amorphous silicon film, and preparing a back reflection composite film on the p-type doped amorphous silicon film. In a preferred embodiment, a first intrinsic amorphous silicon thin film, an n-type doped amorphous silicon thin film, a second intrinsic amorphous silicon thin film and a p-type doped amorphous silicon thin film are prepared on the flexible substrate by vacuum chemical vapor deposition.

According to the preparation method of the high-efficiency double-sided light-receiving flexible silicon heterojunction solar cell, the production cost of the flexible silicon heterojunction solar cell is reduced through the flexible substrate with the thinned absorption layer, so that the flexible silicon heterojunction solar cell can be applied to a special curved surface; the spectral response of the infrared part is improved through the back reflection composite film, and the method has outstanding significance for further obtaining the high-efficiency flexible silicon heterojunction solar cell and expanding the application field of the solar cell. The preparation method of the back reflection structure can be used for improving the photoelectric conversion efficiency of any solar cell lacking infrared response due to the thin absorption layer. Therefore, the invention can reduce the cost and improve the conversion efficiency of the silicon heterojunction solar cell produced in large scale, and has high industrial utilization value.

Drawings

FIG. 1 is a schematic diagram of a double-sided light receiving high-efficiency flexible SHJ solar cell according to the present invention;

FIG. 2 is a flow chart illustrating the fabrication of a back reflection structure;

FIG. 3 is a schematic diagram illustrating the light trapping principle of the back reflection structure on the second light receiving surface;

fig. 4 shows a reflection spectrum of the back reflection structure on the second light receiving surface.

Detailed Description

In this context, a flexible substrate refers to a substrate having a thickness of 100 μm or less.

The preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

Example 1

As shown in fig. 1, the manufacturing method of the method for manufacturing the high-efficiency double-sided light receiving flexible silicon heterojunction solar cell according to the first embodiment of the invention first includes providing a flexible substrate 101, specifically, the flexible substrate 101 has a thickness of 100 μm or less and an area of 125 × 125mm²The n-type single crystal silicon of (2).

As shown in fig. 1, the manufacturing method of the method for manufacturing a high-efficiency double-sided light receiving flexible silicon heterojunction solar cell according to the first embodiment of the invention is followed by performing texturing cleaning on the flexible substrate 101. Specifically, the flexible substrate 101 is anisotropically etched by an alkali solution such as KOH or NaOH to perform surface texturing, and the silicon wafer is cleaned by RCA1 or RCA2 solutions.

As shown in fig. 1, the manufacturing method of the high-efficiency double-sided light-receiving flexible silicon heterojunction solar cell according to the first embodiment of the invention next prepares a first intrinsic amorphous silicon thin film 102 and an n-type doped amorphous silicon thin film 103 on the first surface of the flexible substrate 101, and then prepares a second intrinsic amorphous silicon thin film 104 and a p-type doped amorphous silicon thin film 105 on the second surface of the flexible substrate 101. Specifically, a first intrinsic amorphous silicon thin film 102, an n-type doped amorphous silicon thin film 103, a second intrinsic amorphous silicon thin film 104, and a p-type doped amorphous silicon thin film 105 are prepared on the flexible substrate 101 by vacuum chemical vapor deposition. In a preferred embodiment, the vacuum chemical vapor deposition is a Plasma Enhanced Chemical Vapor Deposition (PECVD) process, the first intrinsic amorphous silicon thin film 102 is 5nm thick, the n-type doped amorphous silicon thin film 103 is 8nm thick, the second intrinsic amorphous silicon thin film 104 is 5nm thick, and the p-type doped amorphous silicon thin film 105 is 10nm thick.

As shown in fig. 1, the manufacturing method of the method for manufacturing a high-efficiency double-sided light-receiving flexible silicon heterojunction solar cell according to the first embodiment of the invention next prepares a first Transparent Conductive Oxide (TCO) film 106 on the n-type doped amorphous silicon film 103 to form a first light-receiving surface. Specifically, the first TCO film 106 is prepared by magnetron sputtering, Reactive Plasma Deposition (RPD), and the like, and the material of the first TCO film 106 is any conductive oxide. In a preferred embodiment, the first TCO film 106 is formed by Reactive Plasma Deposition (RPD) using tungsten doped indium oxide (IWO) as the material for the first TCO film 106, deposited to a thickness of 80 nm.

As shown in fig. 1, the method for manufacturing the high-efficiency double-sided light-receiving flexible silicon heterojunction solar cell according to the first embodiment of the invention next prepares a back reflection composite film 109 composed of a second TCO film 107 and metal nanoparticles 108 to form a second light-receiving surface according to the flowchart shown in fig. 2. Specifically, the thickness d is prepared by magnetron sputtering, Reactive Plasma Deposition (RPD) and the like₁First sub TCO film of d₁The selected range is 20-30 nm, metal films of gold, silver, aluminum and the like are prepared by methods of thermal evaporation, electron beam evaporation, magnetron sputtering and the like, the thickness range is 10-20 nm, and then N is carried out at the temperature of 150-200 DEG C₂、H₂Annealing for 60-90 minutes in different atmospheres such as Ar to form the metal nanoparticles 108, and then preparing the metal nanoparticles 108 with the thickness d by magnetron sputtering, Reactive Plasma Deposition (RPD) and other methods₂Second sub TCO film of d₂The selected range is 40-70 nm, and the thicknesses are d respectively₁And d₂The sub-TCO films together form the second TCO film 107, and the material of the second TCO film 107 is any conductive oxide. In a preferred embodiment, the Reactive Plasma Deposition (RPD) method is used to produce a thickness d₁And d₂Sub TCO film of d₁Is 20nm, d₂60nm, tungsten-doped indium oxide (IWO) is selected as the material of the second TCO film 107, a metal silver film is prepared by a vacuum evaporation method, a mask plate is used for controlling the deposition area of the metal film, the mask plate in the embodiment has three areas of 3mm × 100mm, which respectively correspond to the coverage areas of the screen printing back electrode main grid, the thickness of the deposited metal silver film is 10nm, the coverage proportion of the whole area is 5.7%, and then N at 180 ℃ is used for preparing the metal silver film₂Annealing in the atmosphere to form silver nanoparticles, wherein the annealing time is 60 minutes, and the particle size of the silver nanoparticles formed by annealing is 100-250 nm.

As shown in fig. 1, the method for manufacturing the high-efficiency double-sided light-receiving flexible silicon heterojunction solar cell according to the first embodiment of the invention next performs a test and characterization on the back reflection composite film 109. Specifically, an elliptic polarization spectro-spectrometer is adopted for testing and characterizing, and the component proportion of the oxide and the metal nano particles and the refractive index of the composite film are fitted and calculated through an equivalent medium theory.

As shown in fig. 1, the manufacturing method of the method for manufacturing a high-efficiency double-sided light-receiving flexible silicon heterojunction solar cell according to the first embodiment of the invention next manufactures a front metal grid 110 and a back metal grid 111 on the first TCO film 106 and the composite film 109, respectively. Specifically, a silver grid electrode was prepared by a screen printing method.

Example 2

As shown in fig. 1, the method for manufacturing a high-efficiency double-sided light receiving flexible silicon heterojunction solar cell according to the second embodiment of the invention first includes providing a flexible substrate 101, specifically, the flexible substrate 101 has a thickness of 100 μm or less and an area of 125 × 125mm or 125mm²The n-type single crystal silicon of (2).

As shown in fig. 1, the manufacturing method of the method for manufacturing a high-efficiency double-sided light receiving flexible silicon heterojunction solar cell according to the second embodiment of the invention is followed by performing texturing cleaning on the flexible substrate 101. Specifically, the flexible substrate 101 is anisotropically etched by an alkali solution such as KOH or NaOH to perform surface texturing, and the silicon wafer is cleaned by RCA1 or RCA2 solutions.

As shown in fig. 1, the manufacturing method of the high-efficiency double-sided light-receiving flexible silicon heterojunction solar cell according to the second embodiment of the invention next prepares a first intrinsic amorphous silicon thin film 102 and an n-type doped amorphous silicon thin film 103 on the first surface of the flexible substrate 101, and then prepares a second intrinsic amorphous silicon thin film 104 and a p-type doped amorphous silicon thin film 105 on the second surface of the flexible substrate 101. Specifically, a first intrinsic amorphous silicon thin film 102, an n-type doped amorphous silicon thin film 103, a second intrinsic amorphous silicon thin film 104, and a p-type doped amorphous silicon thin film 105 are prepared on the flexible substrate 101 by vacuum chemical vapor deposition. In a preferred embodiment, the vacuum chemical vapor deposition is a Plasma Enhanced Chemical Vapor Deposition (PECVD) process, the first intrinsic amorphous silicon thin film 102 is 5nm thick, the n-type doped amorphous silicon thin film 103 is 8nm thick, the second intrinsic amorphous silicon thin film 104 is 5nm thick, and the p-type doped amorphous silicon thin film 105 is 10nm thick.

As shown in fig. 1, the manufacturing method of the method for manufacturing a high-efficiency double-sided light-receiving flexible silicon heterojunction solar cell according to the second embodiment of the invention next prepares a Transparent Conductive Oxide (TCO) film 106 on the n-type doped amorphous silicon film 103 to form a first light-receiving surface. Specifically, the first TCO film 106 is prepared by magnetron sputtering, Reactive Plasma Deposition (RPD), and the like, and the material of the first TCO film 106 is any conductive oxide. In a preferred embodiment, the first TCO film 106 is prepared by magnetron sputtering, and indium oxide doped with tin (ITO) is selected as the material of the first TCO film 106, and the deposition thickness is 80 nm.

As shown in fig. 1, the method for manufacturing the high-efficiency double-sided light-receiving flexible silicon heterojunction solar cell according to the second embodiment of the invention next prepares a back reflection composite film 109 composed of a second TCO film 107 and metal nanoparticles 108 to form a second light-receiving surface according to the flowchart shown in fig. 2. Specifically, the thickness d is prepared by magnetron sputtering, Reactive Plasma Deposition (RPD) and the like₁First sub TCO film of d₁The selected range is 20-30 nm, metal films of gold, silver, aluminum and the like are prepared by methods of thermal evaporation, electron beam evaporation, magnetron sputtering and the like, the thickness range is 10-20 nm, and then N is carried out at the temperature of 150-200 DEG C₂、H₂Annealing for 60-90 minutes in different atmospheres such as Ar to form metal nanoparticles 108, and then preparing the metal nanoparticles with the thickness d by magnetron sputtering, Reactive Plasma Deposition (RPD) and other methods₂Second sub TCO film of d₂The selectable range is 50-70 nm, and the thicknesses are d respectively₁And d₂The sub-TCO films together form the second TCO film 107, and the material of the second TCO film 107 is any conductive oxide. In a preferred embodiment, the thicknesses d are respectively prepared by adopting a magnetron sputtering method₁And d₂Sub TCO film of d₁Is 30nm，d₂Selecting Indium Tin Oxide (ITO) as the material of the second TCO film 107, preparing a metal silver film by a magnetron sputtering method, controlling the deposition area of the metal film by a special mask plate, wherein the mask plate has 9 areas with the thickness of 30mm × 30mm, the thickness of the deposited metal silver film is 12nm, the coverage ratio of the whole area is 52%, and then the N at 180℃ is₂Annealing in the atmosphere to form silver nanoparticles, wherein the annealing time is 60 minutes, and the particle size of the silver nanoparticles formed by annealing is 100-290 nm.

As shown in fig. 1, the method for manufacturing the high-efficiency double-sided light-receiving flexible silicon heterojunction solar cell according to the second embodiment of the invention next performs a test and characterization on the back reflection composite film 109. Specifically, an elliptic polarization spectrometer is adopted for testing and characterizing, and the component proportion of the oxide and the metal nano particles and the refractive index of the composite film are fitted and calculated through an equivalent medium theory.

As shown in fig. 1, the manufacturing method of the method for manufacturing a high-efficiency double-sided light-receiving flexible silicon heterojunction solar cell according to the second embodiment of the invention next manufactures a front metal grid 110 and a back metal grid 111 on the first TCO film 106 and the composite film 109, respectively. Specifically, a silver grid electrode was prepared by a screen printing method.

As shown in fig. 3, the back reflection structure on the second light receiving surface prepared by the method of the present invention can effectively manage light reaching the surface of the metal nanoparticles by using the surface plasmon enhancement effect of the metal nanoparticles, effectively extend the light path by multiple high-angle scattering, and improve the optical absorption of the cell. Specifically, the light reaching the surface of the metal nanoparticles includes light entering the cell from the first light receiving surface without being completely absorbed by the cell, light scattered between the particles, light reflected by the rear metal grid, and light entering from the second light receiving surface.

A reflection spectrogram of the back reflection structure on the second light receiving surface prepared by the method is shown in fig. 4, and compared with the TCO film, the back reflection film consisting of the TCO film and the metal nano particles can effectively enhance the reflection of infrared light with a wave band of 800-1200 nm. When the back reflection composite film is applied to the flexible silicon heterojunction solar cell, infrared light of a near-silicon band gap which is not completely absorbed in a single-pass light path can be reflected back to the cell by the back reflection composite film, the light path of the infrared light in the cell is prolonged, the infrared light escape loss caused by thinning of a silicon wafer substrate is reduced, the absorption of the cell to the infrared light is effectively improved, and the infrared spectrum response of the cell is improved.

In a word, the back reflection structure prepared by the method can effectively improve the optical absorption of the double-sided light-receiving flexible silicon heterojunction battery, particularly the spectral response of an infrared band is obviously improved, and therefore the short-circuit current and the conversion efficiency of the flexible silicon heterojunction battery are effectively improved.

The above embodiments are merely preferred embodiments of the present invention, which are not intended to limit the scope of the present invention, and various changes may be made in the above embodiments of the present invention. All simple and equivalent changes and modifications made according to the claims and the content of the specification of the present application fall within the scope of the claims of the present patent application. The invention has not been described in detail in order to avoid obscuring the invention.