CN102244081B - High-stability amorphous silicon/microcrystalline silicon tandem solar cell and manufacturing method thereof - Google Patents

Abstract

A highly stable amorphous silicon/microcrystalline silicon stacked solar cell, consisting of a substrate, a transparent conductive film, a p-type doped window layer P ₁ , and an amorphous silicon/microcrystalline silicon transition region close to the intrinsic Layer I ₁ , n-type doped layer N ₁ , p-type doped window layer P ₂ , microcrystalline silicon intrinsic layer I ₂ , n-type doped layer N ₂ , ZnO layer, metal Al layer, EVA layer, backplane The layers are sequentially formed into a laminated structure, wherein the P ₁ -I ₁ -N ₁ amorphous silicon cell is the top cell, the P ₂ -I ₂ -N ₂ microcrystalline silicon cell is the bottom cell, and the bottom cell current limiting structure is adopted. The advantage of the present invention is that the light absorption coefficient and photosensitivity of the amorphous silicon material prepared close to the amorphous silicon in the amorphous silicon/microcrystalline silicon transition region are similar to those of conventional amorphous silicon, because nano silicon crystals are embedded in the amorphous network Particles, compact structure, reduced light decay, and the use of the bottom cell current limit, good matching; the process is simple to prepare, easy to control, and the stability of the battery is high.

Description

A kind of highly stable amorphous silicon/microcrystalline silicon laminated solar cell and its preparation method

technical field

The invention relates to a silicon-based thin-film solar cell preparation technology, in particular to a high-stability amorphous silicon/microcrystalline silicon stacked solar cell and a preparation method.

Background technique

Solar energy is an inexhaustible renewable energy source, which is of great significance to environmental protection. The effective use of solar energy has become the consensus of mankind. The use of solar energy, especially photovoltaic power generation technology, is the most promising renewable energy technology. Many countries in the world regard the commercial development and utilization of solar photovoltaic power generation as an important development direction.

In addition to the advantages of saving raw materials, low energy consumption, low cost, and easy large-scale production, silicon-based thin-film solar cells also have the advantages of abundant raw materials and no pollution. Due to the light-induced degradation effect of amorphous silicon solar cells, its application is limited. The material order of microcrystalline silicon solar cells is improved, and the degradation is small, and the combination with amorphous silicon can effectively expand the spectral response range, improve the photoelectric conversion efficiency of the cell, and reduce the cost of the cell. The amorphous silicon/microcrystalline silicon tandem solar cell is composed of two single-junction sub-cells connected in series. The total current of the battery is limited by the minimum value of the current of the two sub-cells. Both the top cell and the bottom cell may become the current limiter of the tandem cell. In order to obtain the maximum battery power output, the top and bottom battery currents must satisfy the matching relationship. After exposure to light, both the top cell and the bottom cell have a certain degree of degradation, the degradation rate of the amorphous silicon top cell is greater than that of the microcrystalline silicon bottom cell, and the laminated cell as a whole no longer meets the current matching conditions.

The existing silicon-based thin-film solar cells have been industrialized. Considering the further improvement of silicon-based thin-film cell efficiency and cost reduction, it is of great significance to reduce the degradation rate of amorphous silicon/microcrystalline silicon stacked solar cells and improve the stable efficiency of cells. Significance.

Contents of the invention

The object of the present invention is to address the above existing problems, to provide a highly stable amorphous silicon/microcrystalline silicon stacked solar cell and its preparation method, which can be realized by adjusting the production process without adding any equipment or raw materials. The stability of the battery can be improved, that is, the stable efficiency of the solar battery can be improved, and the cost of the battery can be reduced.

Technical scheme of the present invention:

A high-stability amorphous silicon/microcrystalline silicon stacked solar cell consists of a substrate, a transparent conductive film TCO, a p-type doped window layer P ₁ , and an amorphous silicon/microcrystalline silicon transition region close to the amorphous silicon itself. Intrinsic layer I ₁ , n-type doped layer N ₁ , p-type doped window layer P ₂ , microcrystalline silicon intrinsic layer I ₂ , n-type doped layer N ₂ , ZnO layer, metal Al layer, EVA layer and back The plate layer is composed and sequentially formed a stacked structure, in which the P ₁ -I ₁ -N ₁ amorphous silicon cell is used as the top cell of the stacked cell, and the P ₂ -I ₂ -N ₂ microcrystalline silicon cell is used as the top cell of the stacked cell The bottom cell and the bottom cell are current-limiting structures, and ZnO and Al are used as composite back electrodes.

The substrate is a glass substrate or a transparent plastic substrate.

The backplane layer is glass or plastic.

The current limiting structure of the bottom cell is formed by using the PECVD method to prepare the current density of the amorphous silicon top cell which is 5-20% higher than that of the microcrystalline silicon bottom cell.

A method for preparing the highly stable amorphous silicon/microcrystalline silicon stacked solar cell, the steps are as follows:

1) Amorphous silicon P ₁ -I ₁ -N ₁ top cells are prepared by PECVD on a transparent conductive film substrate with patterns drawn by laser, in which the amorphous silicon/microcrystalline silicon transition region is close to the amorphous silicon- Side preparation I ₁ layer;

2) Prepare a P ₂ -I ₂ -N ₂ microcrystalline silicon bottom cell on an amorphous silicon P ₁ -I ₁ -N ₁ top cell by PECVD method to obtain a stacked cell, and isolate 10~150 cells by laser scribing Battery;

3) Prepare ZnO and Al composite back electrode by PVD method or MOCVD method, and use laser marking to isolate;

4) Make the insulating side of the battery and weld the leads, and then laminate the battery.

The process parameters for preparing the amorphous silicon _I1 layer by the PECVD method are: glow excitation frequency 13.56-100 MHz, reaction gas pressure 0.1-10 Torr, glow power density 10-1000 mW/cm ² , hydrogen-diluted silane concentration SC< 15%, deposition temperature 100~300℃, I ₁ layer thickness 100~50nm.

The process parameters for preparing the microcrystalline silicon _I2 layer by PECVD method are: glow excitation frequency 13.56~100MHz, reaction gas pressure 0.1~10 Torr, glow power density 10~1000mW/cm ² , deposition temperature 100~300°C , Hydrogen-diluted silane concentration SC<10%, I ₂ layer thickness is 500~3000nm.

The beneficial effects of the present invention are:

The light absorption coefficient and photosensitivity of the amorphous silicon material prepared on the side of the amorphous silicon/microcrystalline silicon transition region close to the amorphous silicon are similar to those of conventional amorphous silicon. The electron mobility is greatly improved, the dangling bonds are less, the light decay is reduced, and the stability is greatly improved. The use of the current limiting structure of the bottom cell can improve the current matching after light-induced degradation, and improve the stable efficiency of the amorphous silicon/microcrystalline silicon stacked solar cell. Only by changing some process steps, it can be transplanted to the existing silicon-based thin film battery production line. The whole process is simple and easy to control, and the battery has high stability.

Description of drawings

The accompanying drawing is a schematic structural view of the amorphous silicon/microcrystalline silicon laminated solar cell.

In the figure: 1. Substrate 2. Transparent conductive film TCO 3. P-type doped window layer

4. The amorphous silicon/microcrystalline silicon transition region is close to the intrinsic layer of amorphous silicon 5. n-type doped layer

6. p-type doped window layer 7. microcrystalline silicon intrinsic layer 8. n-type doped layer 9. ZnO layer

10. Metal Al layer 11. EVA layer 12. Backplane layer.

Detailed ways

The technical solution of the present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

An amorphous silicon/microcrystalline silicon stacked solar cell, the structure of which is shown in the accompanying drawings, consists of a substrate 1, a transparent conductive film TCO 2, a p-type doped window layer P ₁ 3, and an amorphous silicon/microcrystalline silicon transition Intrinsic layer I ₁ 4 close to amorphous silicon, n-type doped layer N ₁ 5, p-type doped window layer P ₂ 6, microcrystalline silicon intrinsic layer I ₂ 7, n-type doped layer N ₂ 8 , ZnO layer 9, metal Al layer 10, EVA layer 11 and back plate layer 12 and sequentially form a stacked structure, wherein the P ₁ -I ₁ -N ₁ amorphous silicon cell is used as the top cell of the stacked cell, and the P _{The 2} -I ₂ -N ₂ microcrystalline silicon battery is used as the bottom battery of the laminated battery, and the bottom battery is a current confinement structure, and ZnO and Al are used as the composite back electrode.

Preparation steps:

1) Amorphous silicon P ₁ -I ₁ -N ₁ top cells are prepared by PECVD method on a transparent conductive film substrate with patterns drawn by laser, in which the amorphous silicon/microcrystalline silicon transition region is close to the amorphous silicon side Prepare I ₁ layer;

2) Prepare a P ₂ -I ₂ -N ₂ microcrystalline silicon bottom cell on an amorphous silicon P ₁ -I ₁ -N ₁ top cell by PECVD method to obtain a stacked cell, and isolate 60 sub-cells by laser scribing;

3) Prepare ZnO and Al composite back electrode by PVD method or MOCVD method, and use laser marking to isolate;

4) Make the insulating side of the battery and weld the leads, and then laminate the battery.

In this embodiment, a glass substrate and a glass back plate layer are used. When the intrinsic layer I of the amorphous silicon top cell _{is 1} , the glow excitation frequency is 40.68 MHz, the reaction gas pressure is 1.2 Torr, the concentration of hydrogen-diluted silane is 7%, and the glow excitation frequency is 1.2 Torr. The optical power density is 80mW/cm ² , the processing sample temperature is 180°C, and the film thickness is 260nm. The QE integral current density of the amorphous silicon top cell is 8.23mA/cm ² , and the QE integral current density of the microcrystalline silicon bottom cell is 7.39mA/cm ² .

The amorphous silicon/microcrystalline silicon stacked solar cell prepared in this embodiment has a cell size of 0.79 m ² , a cell efficiency of 7.16%, and a decay rate of less than 10%.

The significance of the present invention is that when the pin-type amorphous silicon top cell is deposited, the intrinsic layer _I1 is deposited on the side of the amorphous silicon/microcrystalline silicon transition region close to the amorphous silicon by adjusting the hydrogen-diluted silane concentration. The amorphous silicon material has a compact structure and a small light-induced degradation rate. The current limit of the microcrystalline silicon bottom cell is used. The current of the amorphous silicon top cell is greater than the current of the microcrystalline silicon bottom cell, forming a current limiting structure of the bottom cell, so that the current of the top and bottom cells can be matched after light-induced degradation, and the stability of the battery is improved. sex.

Claims (6)

1. A high-stability amorphous silicon/microcrystalline silicon stacked solar cell, characterized in that: by substrate, transparent conductive film TCO, p-type doped window layer P ₁ , amorphous silicon/microcrystalline silicon transition region Intrinsic layer I ₁ near amorphous silicon, n-type doped layer N ₁ , p-type doped window layer P ₂ , microcrystalline silicon intrinsic layer I ₂ , n-type doped layer N ₂ , ZnO layer, metal Al layer, EVA layer and back plate layer and sequentially form a laminated structure, in which the P ₁ -I ₁ -N ₁ amorphous silicon battery is used as the top battery of the laminated battery, and the P ₂ -I ₂ -N ₂ microcrystalline silicon The battery is used as the bottom cell of the laminated cell and the bottom cell is a current-limited structure, with ZnO and Al as the composite back electrode, and the current density of the bottom cell current-limited structure is higher than that of the microcrystalline silicon top cell through the amorphous silicon prepared by the PECVD method. The current density of the bottom battery is 5-20%. 2. The high-stability amorphous silicon/microcrystalline silicon stacked solar cell according to claim 1, wherein the substrate is a glass substrate or a transparent plastic substrate. 3. The high-stability amorphous silicon/microcrystalline silicon stacked solar cell according to claim 1, characterized in that: the back plate layer is made of glass or plastic. 4. A preparation method for high-stability amorphous silicon/microcrystalline silicon laminated solar cell as claimed in claim 1, characterized in that the steps are as follows: 1) Amorphous silicon P ₁ -I ₁ -N ₁ top cells are prepared by PECVD on a transparent conductive film substrate with patterns drawn by laser, in which the amorphous silicon/microcrystalline silicon transition region is close to the amorphous silicon- Side preparation I ₁ layer; 2) Prepare a P ₂ -I ₂ -N ₂ microcrystalline silicon bottom cell on an amorphous silicon P ₁ -I ₁ -N ₁ top cell by PECVD method to obtain a stacked cell, and isolate 10 to 150 cells by laser scribing Battery; 3) Prepare ZnO and Al composite back electrode by PVD method or MOCVD method, and use laser marking to isolate; 4) Make the insulating side of the battery and weld the leads, and then laminate and package the battery. 5. according to the preparation method of the described high-stability amorphous silicon/microcrystalline silicon laminated solar cell of claim 5, it is characterized in that: the process parameter that adopts PECVD method to prepare amorphous silicon I ₁ layer is: glow excitation Frequency 13.56-100MHz, reaction gas pressure 0.1-10Torr, glow power density 10-1000mW/cm ² , hydrogen-diluted silane concentration SC<15%, deposition temperature 100-300°C, I ₁ layer thickness 100-50nm. 6. according to the preparation method of the described high-stability amorphous silicon/microcrystalline silicon laminated solar cell of claim 5, it is characterized in that: the process parameter that adopts PECVD method to prepare microcrystalline silicon I ₂ layers is: glow excitation The frequency is 13.56-100MHz, the reaction gas pressure is 0.1-10Torr, the glow power density is 10-1000mW/cm ² , the deposition temperature is 100-300°C, the hydrogen-diluted silane concentration SC is less than 10%, and the I ₂ layer thickness is 500-3000nm.

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