P-type crystalline silicon solar cell with front surface and back surface in full-area contact passivation and preparation method thereof
阅读说明：本技术 一种正背面全面积接触钝化的p型晶硅太阳电池及其制备方法 (P-type crystalline silicon solar cell with front surface and back surface in full-area contact passivation and preparation method thereof ) 是由 万义茂 袁声召 崔艳峰 黄强 林海峰 于 2019-08-29 设计创作，主要内容包括：本发明涉及太阳电池制备技术领域,尤其是一种正面和背面都全面积接触钝化的P型晶硅太阳电池及其制备方法；包括衬底,衬底采用P型单晶硅片,电池的正面包含发射极,即pn结区；正面全面积接触钝化的隧穿氧化硅/n型掺杂多晶硅区,以及背面全面积接触钝化的隧穿氧化硅/p型掺杂多晶硅区,其中pn结区和隧穿氧化硅/n型掺杂多晶硅区上有正面减反层；电池的背面有背面保护层,电池正面的局域接触钝化有隧穿氧化硅/n型掺杂多晶硅区与金属电极接触；电池的背面局域接触钝化的隧穿氧化硅/P型掺杂多晶硅区与金属电极接触；本发明中的电池采用隧穿氧化硅/多晶硅叠层的选择性载流子输运特性,实现正面和背面的局域接触钝化,从而在保证金属电极的欧姆接触的同时,完全消除金属区复合,从而极大的提高电池的转换效率。(The invention relates to the technical field of solar cell preparation, in particular to a P-type crystalline silicon solar cell with full-area contact passivation on the front surface and the back surface and a preparation method thereof; the solar cell comprises a substrate, wherein the substrate is a P-type monocrystalline silicon wafer, and the front side of the cell comprises an emitter, namely a pn junction region; the front surface full-area contact passivation tunneling silicon oxide/n-type doped polysilicon region and the back surface full-area contact passivation tunneling silicon oxide/p-type doped polysilicon region, wherein the pn junction region and the tunneling silicon oxide/n-type doped polysilicon region are provided with front surface antireflection layers; the back surface of the battery is provided with a back surface protective layer, and a tunneling silicon oxide/n-type doped polycrystalline silicon region is passivated in local contact on the front surface of the battery and is contacted with the metal electrode; the tunneling silicon oxide/P-type doped polysilicon region of the local contact passivation on the back surface of the battery is contacted with the metal electrode; the cell of the invention adopts the selective carrier transport characteristic of the tunneling silicon oxide/polysilicon lamination to realize the local contact passivation of the front surface and the back surface, thereby completely eliminating the recombination of a metal area while ensuring the ohmic contact of a metal electrode, and greatly improving the conversion efficiency of the cell.)
1. The utility model provides a front and the comprehensive passivation contact high-efficient P type crystal silicon solar cell in back which characterized in that: the solar cell comprises a P-type monocrystalline silicon wafer substrate, wherein the front side of the cell comprises an emitter, namely a pn junction region, and a tunneling silicon oxide/n-type doped polycrystalline silicon region with full-area contact passivation, wherein a front side antireflection layer is arranged on the pn junction region and the tunneling silicon oxide/n-type doped polycrystalline silicon region; the back surface of the battery is provided with a tunneling silicon oxide/p-type doped polysilicon region with full-area contact passivation and a back surface protection layer, and the tunneling silicon oxide/n-type doped polysilicon region with local contact passivation on the front surface of the battery is in contact with the metal electrode; the local contact passivated tunneling silicon oxide/p-type doped polysilicon region on the back side of the cell is in contact with the metal electrode.
2. The front-back side full passivation contact high efficiency P-type crystalline silicon solar cell of claim 1, wherein: the tunneling silicon oxide/doped polycrystalline silicon layer with the full-area contact passivation is a full-area structure formed by depositing doped amorphous silicon through a Plasma Enhanced Chemical Vapor Deposition (PECVD) method.
3. The front-back side full passivation contact high efficiency P-type crystalline silicon solar cell of claim 1, wherein: the thickness of the tunneling silicon oxide with the full-area contact passivation is less than 2nm, and the thickness of the n-type doped polycrystalline silicon layer and the thickness of the p-type doped polycrystalline silicon layer are respectively 5-50 nm.
4. The front-back side full passivation contact high efficiency P-type crystalline silicon solar cell of claim 1, wherein: the pn junction includes a lightly doped high sheet resistance region and an n-type doped polysilicon layer contacting the passivation region.
5. The P-type crystalline silicon solar cell with front and back full-area contact passivation of claim 1, wherein: the front antireflection layer adopts a front SiN film or a SiON/SiN laminated film, the thickness of the front SiON film is 10-80nm, and the thickness of the front SiN film is 50-100 nm.
6. The P-type crystalline silicon solar cell with front and back full-area contact passivation of claim 1, wherein: the back surface protection layer comprises a SiN film or an alumina/SiN film, the thickness of the alumina film is 1-50nm, and the thickness of the back surface SiN is 50-200 nm.
7. A preparation method of a P-type crystalline silicon solar cell with front and back full-area contact passivation is characterized by comprising the following steps: the preparation method comprises the following steps:
(1) the battery adopts a P-type monocrystalline silicon wafer as a substrate, the resistivity of the silicon wafer is greater than 0.2ohm.cm, the texturing treatment is firstly carried out, the used solution is KOH solution, and the temperature is 80 ℃; then cleaning the silicon wafer in 2-5% HF solution to clean the surface of the silicon wafer;
(2) the front side of the cell forms a pn junction: firstly, carrying out phosphorus diffusion treatment at the diffusion temperature of 700-;
(3) the back side of the cell is etched to remove the excess pn junction grown around: by using HF/HNO3Mixed acid solution is etched awayThe pn junction on the back and the edge is treated with HF, and the phosphosilicate glass PSG on the surface is removed;
(4) sequentially growing front tunneling silicon oxide/N-doped amorphous silicon and back tunneling silicon oxide/P-doped amorphous silicon on two sides of the cell through PECVD; wherein the N-type doping source comprises phosphorus, the P-type doping source comprises boron or gallium, the thickness of the doped amorphous silicon film is 5-50nm, and the growth temperature is 200-600 ℃;
(5) the battery deposited with the amorphous silicon film in the step (4) enters a high-temperature furnace for crystallization at the temperature of 500-;
(6) growing an anti-reflection layer on the front side of the battery, and growing a protective layer on the back side of the battery;
(7) opening the film on the back by adopting laser, opening the protective layer film by adopting the laser, and performing screen printing to form ohmic contact of a local aluminum back surface field metal region; and printing aluminum paste on the front emitting area.
8. The method for preparing the front-back full-area contact passivated P-type crystalline silicon solar cell according to claim 7, characterized in that: the KOH solution comprises KOH, an additive and H according to the mass ratio2And (3) preparing at a ratio of O =20:3: 160.
9. The method for preparing the front-back full-area contact passivated P-type crystalline silicon solar cell according to claim 7, characterized in that: the step (5) of growing the anti-reflection layer or the protective layer on the front surface and the back surface of the battery specifically comprises the following steps: the front antireflection layer adopts PECVD to deposit an SiN film or an SiON/SiN laminated film, the thickness of the front SiON film is 10-80nm, and the thickness of the front SiN film is 50-100 nm; the back protective layer comprises an ALD or PECVD deposited alumina film and a back SiN film, wherein the thickness of the alumina film is 1-50nm, and the thickness of the back SiN film is 50-200 nm.
10. The method for preparing the front-back full-area contact passivated P-type crystalline silicon solar cell according to claim 7, characterized in that: in the step (7), during screen printing and sintering, the width of the slurry is controlled to be less than 50 μm, the height is controlled to be greater than 5 μm, the sintering peak temperature is about 700-800 ℃, and the time is 20-50 seconds.
Technical Field
The invention relates to the technical field of solar cell preparation, in particular to a P-type crystalline silicon solar cell with front and back surfaces in full-area contact passivation and a preparation method thereof.
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.
In the current industry, the selective emitter formed by overlapping laser doping of the PERC battery can reach 22%. How to further improve the battery efficiency becomes an urgent problem to be solved. The analysis of the structure of the PERC battery shows that the back surface of the PERC battery adopts back surface passivation, so that the back surface recombination can be effectively reduced, the open-circuit voltage can be improved, the back surface reflection can be increased, the short-circuit current can be improved, and the battery efficiency can be improved; 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 above, the recombination bottleneck of the PERC cell results from recombination leaving only the passivation-free 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.
Disclosure of Invention
The purpose of the invention is: the P-type crystalline silicon solar cell adopts the selective carrier transport characteristic of tunneling silicon oxide/polycrystalline silicon lamination to realize the full-area contact passivation, ensures the ohmic contact of a metal electrode, and completely eliminates the metal area recombination, thereby greatly improving the conversion efficiency of the cell, and being suitable for large-scale industryThe crystalline silicon battery prepared by the invention is named as a Polysilicon Passivated Emitter and Rear Cell, and the registered trademark is P2ERC。
In order to solve the technical problems, the technical scheme adopted by the invention is as follows:
a front-side and back-side comprehensive passivation contact high-efficiency P-type crystalline silicon solar cell comprises a P-type monocrystalline silicon wafer substrate, wherein the front side of the cell comprises an emitter, namely a pn junction region, and a full-area contact passivation tunneling silicon oxide/n-type doped polycrystalline silicon region, wherein a front side antireflection layer is arranged on the pn junction region and the tunneling silicon oxide/n-type doped polycrystalline silicon region; the back surface of the battery is provided with a tunneling silicon oxide/p-type doped polysilicon region with full-area contact passivation and a back surface protection layer, and the tunneling silicon oxide/n-type doped polysilicon region with local contact passivation on the front surface of the battery is in contact with the metal electrode; the local contact passivated tunneling silicon oxide/p-type doped polysilicon region on the back side of the cell is in contact with the metal electrode.
Further, the tunneling silicon oxide/doped polysilicon layer with full-area contact passivation is a full-area structure formed by depositing doped amorphous silicon through a Plasma Enhanced Chemical Vapor Deposition (PECVD) method.
Further, the thickness of the tunneling silicon oxide with full-area contact passivation is less than 2nm, and the thickness of the n-type doped polycrystalline silicon layer and the thickness of the p-type doped polycrystalline silicon layer are respectively 5-50 nm.
Further, the pn junction comprises a lightly doped high sheet resistance region and an n-type doped polysilicon layer contacting the passivation region.
Furthermore, the front antireflection layer adopts a front SiN film or a SiON/SiN laminated film, the thickness of the front SiON film is 10-80nm, and the thickness of the front SiN film is 50-100 nm.
Further, the back surface protection layer comprises a SiN film or an alumina/SiN film, the thickness of the alumina film is 1-50nm, and the thickness of the back surface SiN film is 50-200 nm.
A preparation method of a P-type crystalline silicon solar cell with front and back full-area contact passivation comprises the following steps:
(1) the battery adopts a P-type monocrystalline silicon wafer as a substrate, the resistivity of the silicon wafer is greater than 0.2ohm.cm, the texturing treatment is firstly carried out, the used solution is KOH solution, and the temperature is 80 ℃; then cleaning the silicon wafer in 2-5% HF solution to clean the surface of the silicon wafer;
(2) the front side of the cell forms a pn junction: firstly, carrying out phosphorus diffusion treatment at the diffusion temperature of 700-;
(3) the back side of the cell is etched to remove the excess pn junction grown around: by using HF/HNO3Etching the pn junction on the back and the edge by using a mixed acid solution, and then removing the PSG on the surface by passing HF;
(4) sequentially growing front tunneling silicon oxide/N-doped amorphous silicon and back tunneling silicon oxide/P-doped amorphous silicon on two sides of the cell through PECVD; wherein the N-type doping source comprises phosphorus, the P-type doping source comprises boron or gallium, the thickness of the doped amorphous silicon film is 5-50nm, and the growth temperature is 200-600 ℃;
(5) the battery deposited with the amorphous silicon film in the step (4) enters a high-temperature furnace for crystallization at the temperature of 500-;
(6) growing an anti-reflection layer on the front side of the battery, and growing a protective layer on the back side of the battery;
(7) opening the film on the back by adopting laser, opening the protective layer film by adopting the laser, and performing screen printing to form ohmic contact of a local aluminum back surface field metal region; and printing aluminum paste on the front emitting area.
Further, the KOH solution is prepared from the following components in percentage by mass2And (3) preparing at a ratio of O =20:3: 160.
Further, the growing the anti-reflection layer or the protective layer on the front surface and the back surface of the battery in the step (5) specifically comprises: the front antireflection layer adopts PECVD to deposit an SiN film or an SiON/SiN laminated film, the thickness of the front SiON film is 10-80nm, and the thickness of the front SiN film is 50-100 nm; the back protective layer comprises an ALD or PECVD deposited alumina film and a back SiN film, wherein the thickness of the alumina film is 1-50nm, and the thickness of the back SiN film is 50-200 nm.
Further, during the screen printing and sintering in the step (7), the width of the slurry is controlled to be less than 50 μm, the height is controlled to be greater than 5 μm, the sintering peak temperature is about 700-800 ℃, and the time is 20-50 seconds.
The technical scheme adopted by the invention has the beneficial effects that:
the battery of the invention adopts the selective carrier transport characteristic of the tunneling silicon oxide/polysilicon lamination to realize local contact passivation, thereby completely eliminating the recombination of a metal area while ensuring the ohmic contact of a metal electrode, and greatly improving the conversion efficiency of the battery. The battery provided by the invention is suitable for large-scale industrial application, and can greatly improve the conversion efficiency of the PERC battery and reduce the electricity consumption cost.
Drawings
Fig. 1 is a schematic layer structure diagram of a front-back full-area contact passivated P-type crystalline silicon solar cell in the invention.
In the figure: the solar cell comprises a substrate 1, a
Detailed Description
The present invention will now be described in further detail with reference to the accompanying drawings. These drawings are simplified schematic views illustrating only the basic structure of the present invention in a schematic manner, and thus show only the constitution related to the present invention.