Contact structure of solar cell, method of manufacturing and solar cell

Abstract

The application relates to the technical field of photovoltaic cells, and provides a contact structure of a solar cell, a preparation method and the solar cell, wherein the preparation method of the contact structure of the solar cell comprises the following steps: depositing a passivation medium film on the surface of a silicon substrate; coating metal paste on a target area of the passivation medium film, the metal paste containing corrosion components capable of corroding the passivation medium film, and the thickness of the passivation medium film in the target area is reduced by adopting a sintering process, the metal paste forms an electrode grid line, and the thickness of the passivation medium film in the target area is greater than zero; guiding charges are applied on the electrode grid line, the guiding charges are set to be different from the charges of non-equilibrium carriers capable of being generated in the silicon substrate, and the passivation medium film in a non-target area is irradiated by using a light source. In this way, the problem that the recombination loss of the metal contact area of the solar cell in the prior art is high is solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of photovoltaic cells, in particular to a contact structure of a solar cell, a preparation method and the solar cell. BACKGROUND

[0002] The solar cell is a kind of semiconductor device that can directly generate electricity by using sunlight, which can convert light energy into electrical energy through photovoltaic effect. With the continuous development of solar cell technology, the recombination loss of the metal contact area has become one of the important factors restricting the improvement of the conversion efficiency of the solar cell.

[0003] In the prior art, when preparing the metal contact area, a passivation medium film is first processed on the surface of the silicon substrate, then a metal paste (silver paste, aluminum paste, etc.) is printed on the passivation medium film, and through a sintering process, the passivation medium film of the area on the silicon substrate where the metal paste is printed is completely burned through, so that the metal paste is in direct contact with the surface of the silicon substrate, thereby obtaining the metal contact area. The area where the passivation medium film is burned through does not form an ohmic contact, and there is a redundant area without passivation medium film and ohmic contact. The part in the redundant area where the ohmic contact is not formed loses the passivation medium film, which leads to the increase of the recombination of the metal contact area and limits the improvement of the conversion efficiency of the solar cell.

[0004] Therefore, how to solve the problem of high recombination loss of the metal contact area of the solar cell in the prior art has become an important technical problem to be solved by the technical personnel in the field. SUMMARY

[0005] The present application provides a contact structure of a solar cell, a preparation method and the solar cell to solve the defect of high recombination loss of the metal contact area of the solar cell in the prior art.

[0006] The present application provides a preparation method of a contact structure of a solar cell, comprising:

[0007] depositing and forming a passivation medium film on the surface of the silicon substrate;

[0008] applying a metal paste to a target area of the passivation medium film, the metal paste containing an etching component capable of etching the passivation medium film, and reducing the thickness of the passivation medium film in the target area by a sintering process, the metal paste forming an electrode grid line, and the thickness of the passivation medium film in the target area being greater than zero;

[0009] applying a guide charge to the electrode grid line, the guide charge being set to be different from the charge of the non-equilibrium carriers that can be generated in the silicon substrate, and using a light source to irradiate the passivation medium film in a non-target area.

[0010] A method for preparing a contact structure of a solar cell is provided, and the method comprises the following steps:

[0011] A first dielectric film is deposited on the surface of the silicon substrate, and the first dielectric film is a silicon oxide dielectric film;

[0012] A second dielectric film is deposited on the surface of the first dielectric film, and the second dielectric film at least comprises a silicon nitride dielectric film.

[0013] The method further comprises the following steps before the step of depositing the second dielectric film on the surface of the first dielectric film:

[0014] The first dielectric film is bombarded by plasma to reduce the density of the first dielectric film.

[0015] The second dielectric film further comprises an aluminum oxide dielectric film, and the step of depositing the second dielectric film on the surface of the first dielectric film comprises the following steps:

[0016] The aluminum oxide dielectric film is deposited on the surface of the first dielectric film;

[0017] The silicon nitride dielectric film is deposited on the surface of the aluminum oxide dielectric film.

[0018] The method further comprises the following steps of reducing the thickness of the passivation dielectric film in the target region by using a sintering process:

[0019] The sintering temperature is controlled so that the corrosion component in the metal paste can only completely corrode the second dielectric film.

[0020] The thickness of the first dielectric film is 1-5 nanometers, the thickness of the second dielectric film is 70-90 nanometers, and the sintering temperature is less than or equal to 650 degrees Celsius.

[0021] The method further comprises the following steps before the step of depositing the passivation dielectric film on the surface of the silicon substrate:

[0022] The surface of the silicon substrate is cleaned and polished.

[0023] The light source is a laser light source, an LED light source, or a xenon lamp light source.

[0024] The application further provides a contact structure of a solar cell, comprising:

[0025] a silicon substrate;

[0026] a passivation medium film arranged on a surface of the silicon substrate;

[0027] an electrode grid line comprising a body part and a plurality of contact parts, the body part and the contact parts being embedded in the passivation medium film, the body part having a spacing from the silicon substrate, the contact parts being located between the body part and the silicon substrate, the contact parts being in electrical contact with the body part, and each of the contact parts forming an ohmic contact with the silicon substrate.

[0028] The application further provides a solar cell comprising the contact structure of the solar cell.

[0029] The preparation method of the contact structure of the solar cell provided by the application comprises the following steps: depositing a passivation medium film on a surface of a silicon substrate, coating a metal paste on a target region of the passivation medium film, and performing sintering treatment on the silicon substrate, the passivation medium film and the metal paste. Since the metal paste contains an etching component capable of etching the passivation medium film, the thickness of the passivation medium film in the target region can be reduced during the sintering treatment. The metal paste forms an electrode grid line after the sintering treatment. A guide charge different from the charge of the non-equilibrium carriers generated in the silicon substrate is applied to the electrode grid line, and a light source is used to irradiate the passivation medium film in a non-target region. Under the irradiation of the light source, the non-equilibrium carriers are induced in the silicon substrate, and a local current is formed under the action of the guide charge, so that a local high temperature is generated in the passivation medium film. The passivation medium film between the electrode grid line and the silicon substrate is locally sintered and perforated to form a pinhole structure. The metal of the electrode grid line and the silicon substrate are in contact with each other at the pinhole structure to form a metal contact region. The metal contact region at the pinhole structure constitutes a conductive channel between the electrode grid line and the silicon substrate. In this way, the formation of the metal contact region mainly depends on the local high temperature generated by the local current, so that the metal contact region formed as the conductive channel is an ohmic contact. In the position where no local current is generated, no local high temperature is generated, and correspondingly, the passivation medium film still exists in this position, and no metal contact region is formed. Thus, the redundant region without the passivation medium film and the ohmic contact is completely eliminated, the recombination of the metal contact region is reduced, the recombination loss of the contact structure of the solar cell is reduced, and the problem of high recombination loss of the metal contact region of the solar cell in the prior art is solved. BRIEF DESCRIPTION OF DRAWINGS

[0030] In order to more clearly illustrate the technical solutions of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings described below are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without any creative effort based on these drawings.

[0031] Fig. 1 is a flow chart of the preparation method of the contact structure of the solar cell provided by the present application;

[0032] Fig. 2 is a structural schematic diagram of the contact structure of the solar cell provided by the present application.

[0033] Reference signs:

[0034] 1: silicon substrate; 2: electrode grid line; 21: body part; 22: contact part; 3: first dielectric film; 4: second dielectric film. DETAILED DESCRIPTION

[0035] In order to make the objects, technical solutions and advantages of the present application clearer, the following will combine the drawings in the present application to clearly and completely describe the technical solutions in the present application. Obviously, the described embodiments are only some embodiments of the present application, not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without any creative effort are within the protection scope of the present application.

[0036] The following will combine Figs. 1-2 to describe the preparation method of the contact structure of the solar cell of the present application.

[0037] As shown in Fig. 1 and Fig. 2 , the preparation method of the contact structure of the solar cell provided by the present application mainly includes the following steps:

[0038] Step 110, depositing and forming a passivation dielectric film on the surface of the silicon substrate.

[0039] N-type monocrystalline silicon can be selected as the silicon substrate 1, and P-type monocrystalline silicon can also be selected as the silicon substrate 1.

[0040] The passivation dielectric film can be a silicon nitride dielectric film, or a silicon oxide dielectric film and a silicon nitride dielectric film arranged in an overlapping manner.

[0041] The present embodiment mainly adopts a plasma enhanced chemical vapor deposition process (referred to as PECVD process) to deposit the passivation dielectric film on the surface of the silicon substrate 1.

[0042] The PECVD process is to ionize the gas containing the passivation medium film component atoms by means of microwave or radio frequency in the electrode part of the PECVD cavity, to locally form plasma, and the plasma has strong chemical activity and is easy to react, so as to deposit the desired medium film on the silicon substrate 1.

[0043] It should be noted that the above-mentioned principle of film plating by PECVD process is a mature existing technology for those skilled in the art, which will not be described here.

[0044] Step 120, coating a metal paste on the target area of the passivation medium film, the metal paste containing an etching component capable of etching the passivation medium film, and reducing the thickness of the passivation medium film in the target area by sintering process, the metal paste forming an electrode grid line, and the thickness of the passivation medium film in the target area being greater than zero.

[0045] After the passivation medium film is deposited on the surface of the silicon substrate 1, a metal paste is coated at the position where the electrode grid line 2 is needed to be formed, so as to form the electrode grid line 2 by sintering process.

[0046] The above-mentioned position where the electrode grid line 2 is needed to be formed is called the target area.

[0047] The screen printing technology can be selected to print the metal paste on the passivation medium film, at this time, a screen stencil with a hollow area corresponding to the above-mentioned target area needs to be selected.

[0048] The above-mentioned metal paste needs to contain an etching component capable of etching the passivation medium film, so as to reduce the thickness of the passivation medium film in the target area by etching the passivation medium film during the sintering process.

[0049] During the sintering process, the sintering temperature and the sintering time need to be controlled to ensure that the remaining thickness of the passivation medium film in the target area is within the range of 1-5 nanometers, so as to avoid the passivation medium film in the target area being directly burned through.

[0050] The above-mentioned sintering temperature needs to be controlled at 650 degrees Celsius or below.

[0051] The above-mentioned metal paste can be silver paste, aluminum paste or silver aluminum paste mixed with glass powder, and the glass powder can be used as the above-mentioned etching component.

[0052] Step 130, applying a guide charge on the electrode grid line, the guide charge being set to be different from the charge of the non-equilibrium carriers capable of being generated in the silicon substrate, and using a light source to irradiate the passivation medium film in the non-target area.

[0053] After the above-mentioned sintering process is completed, a guide charge is applied on the formed electrode grid line, and a light source is used to irradiate the passivation medium film in the non-target area.

[0054] The above-mentioned guiding charge can be applied by connecting the electrode to the electrode grid line 2, and the voltage formed is controlled at 12 V (V: volt, unit of voltage).

[0055] If the N-type monocrystalline silicon is selected as the silicon substrate 1, the positive electrode can be connected to the electrode grid line 2; if the P-type monocrystalline silicon is selected as the silicon substrate 1, the negative electrode can be connected to the electrode grid line 2.

[0056] The above-mentioned light source can be a natural light source, or an artificial light source such as a laser light source, an LED light source, or a xenon lamp light source.

[0057] When the laser light source is selected as the above-mentioned light source, the light intensity of the laser light source can be controlled to be greater than or equal to 20 times the solar constant, the power is 0.5 W (W: watt, unit of power), the wavelength of the laser light source is 1062 nm, and the irradiation time can be 10 seconds.

[0058] After the light source irradiates the passivation medium film in the non-target area, non-equilibrium carriers are excited and induced in the silicon substrate 1. The above-mentioned guiding charge is different from the charge of the non-equilibrium carriers in the silicon substrate 1, and has an attractive effect on the non-equilibrium carriers in the silicon substrate 1, so as to form a local current. The guiding charge and the non-equilibrium carriers in the silicon substrate 1 are neutralized, which generates a local high temperature in the passivation medium film, so as to locally burn the passivation medium film between the electrode grid line 2 and the silicon substrate 1 to form a pinhole structure. The metal of the electrode grid line 2 and the silicon substrate 1 are mutually expanded at the pinhole structure to contact each other, forming a metal contact area. The metal contact area at the above-mentioned pinhole structure constitutes a conductive channel between the electrode grid line 2 and the silicon substrate 1.

[0059] In this way, the formation of the above-mentioned metal contact area mainly relies on the local high temperature generated by the local current, so that the above-mentioned metal contact area as a conductive channel is all ohmic contact. In the position where no local current is generated, no local high temperature is generated, and correspondingly, the passivation medium film still exists in this position, and no metal contact area is formed, thereby completely eliminating the redundant area without passivation medium film and ohmic contact, reducing the recombination of the metal contact area, and thus reducing the recombination loss of the contact structure of the solar cell, and solving the problem of high recombination loss of the metal contact area of the solar cell in the prior art.

[0060] The above-mentioned passivation medium film can be a single-component medium film, for example, a silicon nitride medium film, which can be directly deposited on the silicon substrate 1 to form the silicon nitride medium film.

[0061] Specifically, the silicon substrate 1 is placed in a PECVD chamber, and SiH4 and NH3 are used as the source gas, and the flow rate of SiH4 is controlled to be 500-2000 sccm (sccm is the unit of volume flow rate), and the flow rate of NH3 is controlled to be 3000-10000 sccm, and the power of the deposition process is controlled to be 10000-15000 W.

[0062] The passivation medium film can also be a medium film with multiple components. When the passivation medium film includes two components, the two components are arranged in layers, the medium film close to the surface of the silicon substrate 1 is the first medium film 3, and the medium film far from the surface of the silicon substrate 1 is the second medium film 4. At this time, the first medium film 3 needs to be deposited on the silicon substrate 1 first, and then the second medium film 4 is deposited on the first medium film 3.

[0063] The first medium film 3 can be a silicon oxide medium film, and the second medium film 4 can be a silicon nitride medium film.

[0064] Specifically, the silicon substrate 1 is placed in a PECVD chamber, and SiH4 and N2O are used as the source gas, and the flow rate of SiH4 is controlled to be 400-2000 sccm, and the flow rate of N2O is controlled to be 5000-20000 sccm, and the power of the deposition process is controlled to be 10000-20000 W. After the deposition of the silicon oxide medium film is completed, SiH4 and NH3 are used as the source gas, and the flow rate of SiH4 is controlled to be 500-2000 sccm, and the flow rate of NH3 is controlled to be 3000-10000 sccm, and the power of the deposition process is controlled to be 10000-15000 W.

[0065] During the deposition process, the deposition time also needs to be controlled to control the thickness of the silicon oxide medium film and the thickness of the silicon nitride medium film. The thickness of the silicon oxide medium film is generally controlled to be 1-5 nanometers, and specifically, the deposition time can be controlled to be 50-300 seconds. The thickness of the silicon nitride medium film is generally controlled to be 70-90 nanometers, and specifically, the deposition time can be controlled to be 70-1000 seconds.

[0066] When P-type single crystal silicon is used as the silicon substrate 1, the second medium film 4 also includes an aluminum oxide medium film, and the aluminum oxide medium film is located between the silicon nitride medium film and the silicon oxide medium film.

[0067] The aluminum oxide medium film can be completed by using atomic layer deposition technology (referred to as ALD).

[0068] In the embodiment, after the deposition of the silicon oxide medium film in the PECVD cavity, the silicon substrate 1 with the deposited silicon oxide medium film is placed in the ALD device, trimethylaluminum (chemical formula: C3H9Al) and tetra-chloro-propylene (also known as TMA, molecular formula: C3H2Cl4) are used as the input source, the flow of TMA is controlled to be 1200sccm, and the temperature is controlled to be about 260℃.

[0069] The thickness of the aluminum oxide medium film can be 7nm.

[0070] When the passivation medium film includes the first medium film 3 and the second medium film 4, only the sintering temperature can be controlled, so that the corrosion component in the metal paste can only completely corrode the second medium film 4.

[0071] The temperature required for the corrosion component in the metal paste to corrode the silicon oxide medium film is higher than the temperature required for the corrosion component to corrode the silicon nitride medium film and the aluminum oxide medium film. By controlling the sintering temperature to be lower than the temperature required for the corrosion of the silicon oxide, the corrosion component in the metal paste can only corrode the silicon nitride medium film and the aluminum oxide medium film.

[0072] In the embodiment, the sintering temperature can be controlled to be 650℃ or lower during the sintering process. The corrosion component in the metal paste only has a corrosion effect on the silicon nitride medium film and the aluminum oxide medium film, and cannot corrode the silicon oxide medium film. Therefore, the control accuracy of the sintering time can be reduced at this time. Even if the sintering time is too long, the silicon oxide medium film will not be corroded, the burn-through of the passivation medium film can be effectively avoided, and the damage to the surface microstructure of the silicon substrate 1 can also be avoided.

[0073] In the embodiment, to improve the efficiency of the metal of the electrode grid line 2 and the silicon substrate 1 to form a metal contact area, the first medium film 3 can be a non-dense film. Specifically, before the second medium film 4 is deposited on the surface of the first medium film 3, the first medium film 3 can also be bombarded by plasma, for example, the first medium film 3 is surface treated by a Plasma surface treatment process, so that the first medium film 3 forms a medium film with uniform pinholes, thereby reducing the density of the first medium film 3, and facilitating the improvement of the speed of the passivation medium film between the electrode grid line 2 and the silicon substrate 1 to further form a pinhole structure under the action of local current and local high temperature, improving the rate of forming ohmic contact, and improving the preparation efficiency of the contact structure of the solar cell.

[0074] In the specific embodiment, after the deposition of the first medium film 3 in the PECVD cavity, argon or a mixture of argon and hydrogen is used as the input source, the power of the treatment process is 5000-15000W, and the bombardment time is controlled to be 10-200 seconds.

[0075] To ensure the quality of the deposition of the passivation medium film on the silicon substrate 1, the surface of the silicon substrate 1 needs to be cleaned and polished before the passivation medium film is deposited.

[0076] In specific embodiments, the silicon substrate 1 can be cleaned with an alkali solution and a hydrogen peroxide solution, and polished with an alkali solution and a surfactant.

[0077] The surfactant can be a texturing additive or a polishing additive. The type of surfactant used in polishing the silicon substrate 1 is mature technology known to those skilled in the art, and is not limited herein.

[0078] The following describes the method for preparing the contact structure of the solar cell in the embodiments of the present application in conjunction with the above embodiments. Specific Embodiment One:

[0080] An N-type monocrystalline silicon is used as the silicon substrate 1, which is cleaned with an alkali solution and a hydrogen peroxide solution, and polished with an alkali solution and a surfactant.

[0081] The silicon substrate 1 is placed in a PECVD chamber, SiH4 and NH3 are used as the source gas, the flow rate of SiH4 is controlled at 900 sccm, the flow rate of NH3 is controlled at 7800 sccm, the deposition time is 600 seconds, and a 80-nanometer-thick silicon nitride medium film is formed on the surface of the silicon substrate 1 by using a PECVD process.

[0082] A silver paste is printed on the surface of the silicon nitride medium film by using a screen printing technique, and then the silicon substrate 1 is placed in a sintering furnace, the sintering temperature is controlled at 600 degrees Celsius, the sintering time is 70 seconds, the thickness of the silicon nitride medium film between the silver paste and the silicon substrate 1 is 5 nanometers, and the silver paste forms the electrode grid line 2.

[0083] A positive electrode is connected to the electrode grid line 2, and a laser light source with a power of 0.5 W and a wavelength of 1062 nanometers is used to irradiate the silicon nitride medium film for 10 seconds.

[0084] The contact structure of the solar cell prepared by the above steps has a recombination loss of 149 fA / cm 2 (fA / cm 2 , and a contact resistance of 1.9 mΩ·cm 2 . Specific Embodiment Two:

[0086] An N-type monocrystalline silicon is used as the silicon substrate 1, which is cleaned with an alkali solution and a hydrogen peroxide solution, and polished with an alkali solution and a surfactant.

[0087] The silicon substrate 1 is placed in a PECVD cavity, SiH4 and N2O are used as the input source, the flow rate of SiH4 is controlled at 1000sccm, the flow rate of N2O is controlled at 7000sccm, the deposition time is 100 seconds, and a 1.5 nanometer thick silicon oxide dielectric film is formed on the surface of the silicon substrate 1 by using a PECVD process;

[0088] The silicon oxide dielectric film is bombarded with a mixture of argon and hydrogen as the input source, and the bombardment time is 60 seconds;

[0089] SiH4 and NH3 are used as the input source, the flow rate of SiH4 is controlled at 900sccm, the flow rate of NH3 is controlled at 7800sccm, the deposition time is 600 seconds, and an 80 nanometer thick silicon nitride dielectric film is formed on the surface of the silicon oxide dielectric film by using a PECVD process;

[0090] The silver paste is printed on the surface of the silicon nitride dielectric film by using a screen printing technology, then the silicon substrate 1 is placed in a sintering furnace, the sintering temperature is controlled at 600 degrees Celsius, the sintering time is 90 seconds, the silicon nitride dielectric film between the silver paste and the silicon substrate 1 is completely etched, only the silicon oxide dielectric film remains between the silver paste and the silicon substrate 1, and the above-mentioned silver paste forms the electrode grid line 2;

[0091] The positive electrode is connected to the electrode grid line 2, and the silicon nitride dielectric film is irradiated with a laser light source with a power of 0.5W and a wavelength of 1062 nanometers for 10 seconds.

[0092] The recombination loss of the contact structure of the solar cell prepared by the above steps is 146fA / cm 2 , and the contact resistance is 1.75mΩ·cm 2 . Specific embodiment three:

[0094] The P-type monocrystalline silicon is used as the silicon substrate 1, the silicon substrate 1 is cleaned with an alkali solution and a hydrogen peroxide solution, and the silicon substrate 1 is polished with an alkali solution and a surfactant;

[0095] The silicon substrate 1 is placed in a PECVD cavity, SiH4 and N2O are used as the input source, the flow rate of SiH4 is controlled at 1500sccm, the flow rate of N2O is controlled at 7000sccm, the deposition time is 150 seconds, and a 3 nanometer thick silicon oxide dielectric film is formed on the surface of the silicon substrate 1 by using a PECVD process;

[0096] The silicon oxide dielectric film is bombarded with a mixture of argon and hydrogen as the input source, and the bombardment time is 60 seconds;

[0097] The silicon substrate 1 is placed in an ALD device, trimethylaluminum and tetrachloropropene are used as the inlet source, the flow of tetrachloropropene is controlled to be 1200sccm, the temperature is controlled to be 260 degrees Celsius, and an atomic layer deposition technology is used to form an aluminum oxide dielectric film with a thickness of 7 nanometers on the surface of the silicon oxide dielectric film;

[0098] SiH4 and NH3 are used as the inlet source, the flow of SiH4 is controlled to be 900sccm, the flow of NH3 is controlled to be 7800sccm, the deposition time is 600 seconds, and a PECVD process is used to form a silicon nitride dielectric film with a thickness of 80 nanometers on the surface of the aluminum oxide dielectric film;

[0099] A screen printing technology is used to print silver paste on the surface of the silicon nitride dielectric film, then the silicon substrate 1 is placed in a sintering furnace, the sintering temperature is controlled to be 630 degrees Celsius, the sintering time is 100 seconds, the silicon nitride dielectric film and the aluminum oxide dielectric film between the silver paste and the silicon substrate 1 are completely corroded, only the silicon oxide dielectric film is left between the silver paste and the silicon substrate 1, and the above silver paste forms the electrode grid line 2;

[0100] The positive electrode is connected to the electrode grid line 2, and a laser light source with a power of 0.5W and a wavelength of 1062 nanometers is used to irradiate the silicon nitride dielectric film for 10 seconds.

[0101] The contact structure of the solar cell prepared through the above steps has a recombination loss of 148fA / cm 2 and a contact resistance of 1.8mΩ·cm 2 .

[0102] Through repeated experiments, the contact structure of the solar cell prepared by the preparation method of the contact structure of the solar cell provided in the embodiments of the present application has a contact resistance of not more than 2mΩ·cm 2 and a recombination loss of not more than 150fA / cm 2 , which is only one third of the recombination loss of the contact structure of the solar cell in the prior art.

[0103] On the other hand, based on the same overall inventive concept, the embodiments of the present application also provide a contact structure of a solar cell, which can be mutually referred to with the preparation method of the contact structure of the solar cell described above.

[0104] Referring Fig. 2 , the embodiments of the present application provide a contact structure of a solar cell, which includes a silicon substrate 1, a passivation dielectric film and a cell grid line, and the passivation dielectric film is arranged on the surface of the silicon substrate 1.

[0105] Specifically, the electrode grid line 2 comprises a body part 21 and a plurality of contact parts 22, the body part 21 and the contact part 22 are embedded in the passivation medium film, and the body part 21 has a spacing with the silicon substrate 1, that is, the body part 21 does not penetrate the passivation medium film.

[0106] The contact part 22 is located between the body part 21 and the silicon substrate 1, the contact part 22 is in electrical contact with the body part 21 and can pass current. Each contact part 22 forms an ohmic contact with the silicon substrate 1.

[0107] In this way, the metal contact area between the electrode grid line 2 and the silicon substrate 1 is realized by the contact part 22, each contact part 22 forms an ohmic contact with the silicon substrate 1. The position of the body part 21 except the contact part 22 still has the passivation medium film, and no metal contact area is formed, completely eliminating the redundant area without passivation medium film and ohmic contact, reducing the recombination of the metal contact area, thereby reducing the recombination loss of the contact structure of the solar cell, and solving the problem of high recombination loss of the metal contact area of the solar cell in the prior art.

[0108] The derivation process of the beneficial effects of the contact structure of the solar cell in the embodiment of the present application is similar to the derivation process of the beneficial effects of the preparation method of the contact structure of the solar cell, and thus will not be described here

[0109] In the embodiment, the passivation medium film can be only a silicon nitride medium film, or a silicon nitride medium film and a silicon oxide medium film arranged in overlap, and the silicon oxide medium film is located between the silicon nitride medium film and the silicon substrate 1.

[0110] For the P-type monocrystalline silicon material silicon substrate 1, in addition to the silicon nitride medium film and the silicon oxide medium film, the passivation medium film can further comprise an aluminum oxide medium film, and the aluminum oxide medium film is located between the silicon nitride medium film and the silicon oxide medium film.

[0111] In another aspect, based on the same overall inventive concept, the embodiment of the present application also provides a solar cell comprising the contact structure of the solar cell provided by the above-mentioned embodiment, which has all the advantages of the contact structure of the solar cell. The derivation process of the beneficial effects of the solar cell in the embodiment of the present application is similar to the derivation process of the beneficial effects of the contact structure of the solar cell, and thus will not be described here.

[0112] It should be pointed out finally that the above embodiments are only used to illustrate the technical solutions of the present application, but not to limit the same; and although the present application has been described in detail with reference to the foregoing embodiments, it should be appreciated by those skilled in the art that the technical solutions recorded in the foregoing embodiments can be modified, or some technical features thereof can be replaced equivalently; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A method of fabricating a contact structure of a solar cell, characterized by, The method comprises the following steps: depositing a passivation medium film on the surface of a silicon substrate; applying a metal paste on a target area of the passivation medium film, the metal paste containing a corrosion component capable of corroding the passivation medium film, and reducing the thickness of the passivation medium film in the target area by a sintering process, the metal paste forming an electrode grid line, the thickness of the passivation medium film in the target area being greater than zero; applying a guide charge on the electrode grid line, the guide charge being different from the charge of non-equilibrium carriers capable of being generated in the silicon substrate, and irradiating the passivation medium film in a non-target area by a light source, after the passivation medium film in the non-target area is irradiated by the light source, the non-equilibrium carriers are induced in the silicon substrate, the guide charge has an attraction effect on the non-equilibrium carriers in the silicon substrate to form a local current, the guide charge and the non-equilibrium carriers in the silicon substrate are neutralized, a local high temperature is generated in the passivation medium film, the passivation medium film between the electrode grid line and the silicon substrate is locally burned through to form a pinhole structure, the metal of the electrode grid line and the silicon substrate are mutually expanded at the pinhole structure to contact each other to form a metal contact area, and the metal contact area constitutes a conductive channel between the electrode grid line and the silicon substrate.

2. The method of producing a contact structure of a solar cell according to claim 1, wherein The step of depositing a passivation medium film on the surface of a silicon substrate comprises the following steps: depositing a first medium film on the surface of the silicon substrate, the first medium film being a silicon oxide medium film; depositing a second medium film on the surface of the first medium film, the second medium film comprising at least a silicon nitride medium film.

3. The method of producing a contact structure of a solar cell according to claim 2, wherein Before the step of depositing a second medium film on the surface of the first medium film, the method further comprises the following step: bombarding the first medium film by plasma to reduce the density of the first medium film.

4. The method of producing a contact structure of a solar cell according to claim 2, wherein The second medium film further comprises a silicon oxide medium film, and the step of depositing a second medium film on the surface of the first medium film comprises the following steps: depositing the silicon oxide medium film on the surface of the first medium film; depositing the silicon nitride medium film on the surface of the silicon oxide medium film.

5. The method of claim 2, wherein the method further comprises: The step of reducing the thickness of the passivation medium film in the target area by a sintering process comprises the following step: controlling the sintering temperature so that the corrosion component in the metal paste can only completely corrode the second medium film.

6. The method of producing a contact structure of a solar cell according to claim 5, wherein The thickness of the first medium film is 1-5 nanometers, the thickness of the second medium film is 70-90 nanometers, and the sintering temperature is less than or equal to 650 degrees Celsius.

7. The method of producing a contact structure of a solar cell according to claim 1, wherein Before the step of depositing a passivation medium film on the surface of a silicon substrate, the method further comprises the following step: cleaning and polishing the surface of the silicon substrate.

8. The method of producing a contact structure of a solar cell according to claim 1, wherein The light source is a laser light source, an LED light source, or a xenon lamp light source.

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