阅读说明：本技术 局域接触钝化太阳电池的制备方法 (Preparation method of local contact passivation solar cell ) 是由 袁声召 崔艳峰 庄宇峰 万义茂 黄强 林海峰 于 2019-09-25 设计创作，主要内容包括：本发明属于太阳能电池制备技术领域,尤其涉及一种局域接触钝化太阳电池的制备方法。本发明,依次包括制绒、隧穿氧化硅沉积、掺磷非晶硅栅线印刷、烘干、清洗、磷扩散、刻蚀、钝化层生长、激光开模和丝网印刷及烧结等步骤。本发明采用印刷非晶硅浆料、烘干实现微晶硅的图形化,从而形成局域接触钝化,减少寄生吸收,同时相比于离子注入法具有更低的生产成本,适合大规模产业化应用,并且,本发明制得的太阳能电池板形成有微晶硅/氧化硅叠层结构,以此结构的选择性载流子输运特性来实现接触钝化,保证金属电极的欧姆接触的同时,完全消除金属区复合。(The invention belongs to the technical field of solar cell preparation, and particularly relates to a preparation method of a local contact passivation solar cell. The method sequentially comprises the steps of texturing, tunneling silicon oxide deposition, phosphorus-doped amorphous silicon gate line printing, drying, cleaning, phosphorus diffusion, etching, passivation layer growth, laser die sinking, screen printing, sintering and the like. The method adopts the printing of the amorphous silicon slurry and the drying to realize the imaging of the microcrystalline silicon, thereby forming local contact passivation and reducing parasitic absorption, simultaneously has lower production cost compared with an ion implantation method, is suitable for large-scale industrial application, and the solar cell panel prepared by the method has a microcrystalline silicon/silicon oxide laminated structure, realizes the contact passivation by the selective carrier transport characteristic of the structure, ensures the ohmic contact of a metal electrode, and completely eliminates the recombination of a metal area.)

1. A method for preparing a local contact passivation solar cell is characterized by comprising the following steps:

the method comprises the following steps: texturing, namely, taking a P-type monocrystalline silicon wafer as a silicon substrate, placing the silicon substrate in texturing liquid for texturing treatment, and then cleaning the silicon substrate in hydrofluoric acid to clean the surface of the silicon wafer;

step two: depositing tunneling silicon oxide, namely depositing a layer of tunneling silicon oxide film on both sides of a cleaned silicon wafer by using a thermal oxidation device;

step three: printing a phosphorus-doped amorphous silicon grid line, namely printing the phosphorus-doped amorphous silicon grid line on the front surface of the silicon wafer by a screen printing according to the screen printing plate pattern, wherein the width of the phosphorus-doped amorphous silicon grid line is 100-200 mu m, and the thickness of the phosphorus-doped amorphous silicon grid line is 100-200 nm;

step four: drying, namely drying by using an oxygen-free atmosphere furnace, wherein the oxygen content in the oxygen-free atmosphere furnace is less than 3ppm, and the peak temperature is 500-700 ℃;

step five: cleaning, namely cleaning the surface of the crystal silicon printed with the phosphorus-doped amorphous silicon and the unprinted areas by using hydrofluoric acid;

step six: phosphorus diffusion, namely placing a silicon wafer in a phosphorus diffusion furnace tube to form a pn junction;

step seven: etching to remove the pn junction on the back surface, and cleaning by using hydrofluoric acid to remove the phosphorosilicate glass on the surface;

step eight: growing a passivation layer, namely depositing an alumina film on the back surface of the battery, and then respectively depositing silicon nitride films on the back surface and the front surface;

step nine: opening the die by laser, and opening the silicon nitride film deposited on the back of the battery in the step eight by using the laser;

step ten: and screen printing and sintering, wherein the screen printing and sintering are carried out according to the screen printing plate pattern, the width of the fine grid on the front surface is less than 50 mu m, the height is more than 5 mu m, the sintering peak temperature is about 740-780 ℃, and the time is 30-50s, so that the solar cell is prepared.

2. The method of claim 1, wherein the local contact passivation solar cell comprises: the texturing solution used in the first step is prepared from the following components in percentage by mass: additive for making wool: h₂The ratio of O to O is 20:3:160, and the temperature of the texturing solution is 80 ℃.

3. The method of claim 1, wherein the local contact passivation solar cell comprises: the volume concentration of hydrofluoric acid in the first step and the fifth step is 2-5%.

4. The method of claim 1, wherein the local contact passivation solar cell comprises: in the second step, the thickness of the tunneling silicon oxide film is less than 2nm, and the deposition temperature is 500-700 ℃.

5. The method of claim 1, wherein the local contact passivation solar cell comprises: the diffusion temperature of the phosphorus diffusion temperature in the sixth step is 700-900 ℃.

6. The method of claim 1, wherein the local contact passivation solar cell comprises: and in the step eight, the thickness of the alumina film is 5-25 nm.

7. The method of claim 1, wherein the local contact passivation solar cell comprises: in the eighth step, the thickness of the back silicon nitride film is 100-120nm, and the thickness of the front silicon nitride film is 70-90 nm.

8. The method of claim 1, wherein the local contact passivation solar cell comprises: the second step is replaced by the following steps: soaking the cleaned silicon wafer in a nitric acid solution, wherein the temperature of the nitric acid solution is more than 70 ℃.

Technical Field

The invention belongs to the technical field of solar cell preparation, and particularly relates to a preparation method of a local contact passivation solar cell.

Background

The reduction of manufacturing cost and the improvement of conversion efficiency are always two main lines of development of the photovoltaic industry. The PERC cell is the mainstream production process in the present and future due to its relatively simple process and less cost increase. At present, the mass production efficiency of the PERC cell in the industry is about 21.5%, and the recent selective emitter formed by overlapping laser doping can reach 21.7%. How to further improve the battery efficiency becomes an urgent problem to be solved. Analysis of the structure of the PERC cell it can be seen that the back side of the cell is made of alumina Al₂O₃Passivation can effectively reduce back surface recombination, improve open-circuit voltage, increase back surface reflection and improve short-circuit current, thereby improving the efficiency of the battery; the shallow diffusion region in the selective emitter structure can reduce Auger recombination of the crystalline silicon solar cell and improve spectral response of the solar cell, so that open-circuit voltage and short-circuit current are improved; the heavy diffusion region is beneficial to reducing the contact resistance of the diffusion layer and the metal electrode, so that the series resistance of the solar cell is reduced, and the filling factor is improved. As can be seen from the above, the structure of the PERC cell is already quite perfect, and in particular the recombination has been greatly reduced, leaving only the recombination of the metal regions. How to reduce or even eliminate the recombination of the metal region becomes the key to improve the efficiency of the PERC battery in the future.

In order to solve the problem, research and research are carried out during long-term production and life time, for example, chinese patent application discloses a method for preparing a full-front-side passivation contact high-efficiency P-type crystalline silicon solar cell [ application No.: 201910124067.9], the invention patent application comprises a substrate, the substrate is a P-type monocrystalline silicon wafer, the front side of the battery comprises an emitter, namely a pn junction area, and a tunneling silicon oxide/n-type doped polycrystalline silicon layer with full-area contact passivation, wherein a front passivation layer is arranged on the pn junction area and the tunneling silicon oxide/n-type doped polycrystalline silicon layer; the back side of the battery is provided with a back passivation layer, and the tunneling silicon oxide/n-type doped polycrystalline silicon layer with local contact passivation on the front side of the battery is in contact with the metal electrode; and a sintered aluminum paste layer is arranged in the local area of the back surface of the battery to form an aluminum back surface field. However, the method adopted in this patent application is to passivate the front side full contact, with a large parasitic absorption.

For another example, the chinese patent application discloses a local contact passivated P-type crystalline silicon solar cell and a method for manufacturing the same [ application No.: 201811418678.6], the invention patent application comprises a substrate, the substrate adopts a P-type monocrystalline silicon piece, the front side of the battery comprises an emitter, the emitter is a pn junction area, and a tunneling silicon oxide/n-type doped polycrystalline silicon area with local contact passivation, wherein the pn junction area and the tunneling silicon oxide/n-type doped polycrystalline silicon area with local contact passivation have a front side passivation layer, a silicon oxide/silicon nitride laminated film or a single layer of silicon nitride film; the tunneling silicon oxide/n-type doped polycrystalline silicon region with the passivated local contact is contacted with a metal electrode; the back surface of the battery is provided with a back surface passivation layer, and the back surface passivation layer is an aluminum oxide/silicon nitride laminated film; and the back surface of the battery is also provided with a sintered aluminum paste layer to form an aluminum back surface field. However, the process flow of the patent application adopts an ion implantation method, and local contact passivation can be formed only by combining the ion implantation with an etching process, which results in higher production cost.

Disclosure of Invention

The invention aims to solve the problems and provides a preparation method of a local contact passivation solar cell.

In order to achieve the purpose, the invention adopts the following technical scheme:

a method for preparing a local contact passivation solar cell comprises the following steps:

the method comprises the following steps: texturing, namely, taking a P-type monocrystalline silicon wafer as a silicon substrate, placing the silicon substrate in texturing liquid for texturing treatment, and then cleaning the silicon substrate in hydrofluoric acid to clean the surface of the silicon wafer;

step two: depositing tunneling silicon oxide, namely depositing a layer of tunneling silicon oxide film on both sides of a cleaned silicon wafer by using a thermal oxidation device;

step three: printing a phosphorus-doped amorphous silicon grid line, namely printing the phosphorus-doped amorphous silicon grid line on the front surface of the silicon wafer by a screen printing according to the screen printing plate pattern, wherein the width of the phosphorus-doped amorphous silicon grid line is 100-200 mu m, and the thickness of the phosphorus-doped amorphous silicon grid line is 100-200 nm;

step four: drying, namely drying by using an oxygen-free atmosphere furnace, wherein the oxygen content in the oxygen-free atmosphere furnace is less than 3ppm, and the peak temperature is 500-700 ℃;

step five: cleaning, namely cleaning the surface of the crystal silicon printed with the phosphorus-doped amorphous silicon and the unprinted areas by using hydrofluoric acid;

step six: phosphorus diffusion, namely placing a silicon wafer in a phosphorus diffusion furnace tube to form a pn junction;

step seven: etching to remove the pn junction on the back surface, and cleaning by using hydrofluoric acid to remove the phosphorosilicate glass on the surface;

step eight: growing a passivation layer, namely depositing an alumina film on the back surface of the battery, and then respectively depositing silicon nitride films on the back surface and the front surface;

step nine: opening the die by laser, and opening the silicon nitride film deposited on the back of the battery in the step eight by using the laser;

step ten: and screen printing and sintering, wherein the screen printing and sintering are carried out according to the screen printing plate pattern, the width of the fine grid on the front surface is less than 50 mu m, the height is more than 5 mu m, the sintering peak temperature is about 740-780 ℃, and the time is 30-50s, so that the solar cell is prepared.

In the above method for preparing a local contact passivation solar cell, the texturing solution used in the first step is prepared by mixing, by mass, KOH: additive for making wool: h₂The ratio of O to O is 20:3:160, and the temperature of the texturing solution is 80 ℃.

In the above method for manufacturing a local contact passivated solar cell, the hydrofluoric acid volume concentration in the first step and the fifth step is 2-5%.

In the above method for preparing the local contact passivation solar cell, the thickness of the tunneling silicon oxide film in the second step is less than 2nm, and the deposition temperature is 500-.

In the above method for preparing a local contact passivation solar cell, the diffusion temperature of the phosphorus diffusion temperature in the sixth step is 700-900 ℃.

In the above method for manufacturing a local contact passivation solar cell, in step eight, the thickness of the alumina thin film is 5-25 nm.

In the above method for preparing a local contact passivation solar cell, in the eighth step, the thickness of the back silicon nitride film is 100-120nm, and the thickness of the front silicon nitride film is 70-90 nm.

In the above method for manufacturing a local contact passivated solar cell, the second step is replaced by the following steps: soaking the cleaned silicon wafer in a nitric acid solution, wherein the temperature of the nitric acid solution is more than 70 ℃.

Compared with the prior art, the invention has the advantages that:

1. the method adopts the printing of the amorphous silicon slurry and the drying to realize the imaging of the microcrystalline silicon, thereby forming local contact passivation and reducing parasitic absorption, and meanwhile, compared with an ion implantation method, the method has lower production cost and is suitable for large-scale industrial application.

2. The solar cell panel manufactured by the invention is formed with a microcrystalline silicon/silicon oxide laminated structure, and the contact passivation is realized by the selective carrier transport characteristic of the structure, so that the ohmic contact of a metal electrode is ensured, and the recombination of a metal area is completely eliminated.

3. The invention adopts one-step diffusion to simultaneously form a light diffusion area and activate the passivation of the microcrystalline silicon layer, thereby simplifying the process.

Detailed Description

The present invention will be described in further detail with reference to specific embodiments.