Silicon photovoltaic cell with freewheeling protection function and its manufacturing method and application

Abstract

The present invention relates to the technical field of preparation of pn junction photovoltaic cells with semiconductor crystalline silicon material as substrate, and discloses a silicon photovoltaic cell with freewheeling protection function and its manufacturing method and application, wherein the device comprises an in-situ integrated photoelectric conversion unit pn junction and a Schottky diode MS junction, wherein the Schottky diode MS junction and the photoelectric conversion unit pn junction are in a parallel state with reverse polarity; a third silicon region is arranged between the Schottky diode MS junction and the first silicon region. The device and method provided by the present invention can realize the in-situ freewheeling hot spot protection of a monolithic silicon photovoltaic cell, without the need for external connection, with simplified design and high reliability; the freewheeling diode has a low conduction voltage drop, a large chip perimeter area ratio, a low current density, a small on-resistance, and good heat dissipation conditions; the loss of photogenerated non-equilibrium minority carriers is reduced, which is conducive to maintaining the photoelectric conversion efficiency of the silicon photovoltaic cell.

Description

Technical Field

[0001] This invention relates to the field of pn junction photovoltaic cell fabrication technology using semiconductor crystalline silicon material as a substrate, and more specifically, to a silicon photovoltaic cell with freewheeling protection function, its manufacturing method, and its application. Background Technology

[0002] In photovoltaic technology, photoelectric conversion efficiency, system safety, and manufacturing cost are perpetually pursued goals. Current technologies still have shortcomings in terms of efficiency, safety, and cost, including:

[0003] First, existing technologies cannot achieve in-situ protection of the hot spot effect of silicon photovoltaic cells on the same substrate silicon wafer, and an external freewheeling diode is required.

[0004] Specifically, the smallest unit for bypassing the hot spot effect of existing freewheeling diodes is usually a battery string. Thus, even if only one battery in the string fails, the entire string will be bypassed, which significantly reduces the photoelectric conversion efficiency of the system.

[0005] Although patent CN110165006B uses complementary freewheeling protection to prevent hot spot effects in silicon photovoltaic cells and achieves freewheeling protection for individual cells, it requires at least two silicon photovoltaic cells with two different conductivity types and a freewheeling diode, which increases manufacturing costs.

[0006] Second, existing technology patents such as CN110165006B indicate that the pn junction interface of the freewheeling diode will cause some of the photogenerated non-equilibrium minority carriers to diffuse and recombine, reducing the output current.

[0007] Existing patents, such as CN110165006B, involve photogenerated non-equilibrium minority carriers generated in the base region (substrate silicon wafer or first silicon region). Driven by a concentration gradient, these carriers diffuse to the pn junction region of the bypass diode, recombine in the high recombination region near the junction, forming a recombination current. Alternatively, the photogenerated non-equilibrium minority carriers diffused to the pn junction region of the bypass diode are separated within the pn junction region, generating a photogenerated electromotive force (EMF) across the pn junction. Under the influence of this EMF, the bypass diode enters a subconducting state, shunting a portion of the photogenerated current generated by the silicon photovoltaic cell it protects in parallel. Since neither of these currents can be output to the external circuit, the photoelectric conversion efficiency of the system is reduced to some extent.

[0008] Third, the forward voltage drop of the PN junction in existing silicon freewheeling diodes is relatively large.

[0009] For example, patent CN110165006B uses a silicon pn junction to provide complementary freewheeling protection for a single silicon photovoltaic cell. The silicon pn junction has a large forward voltage drop, and the high forward voltage drop of the freewheeling diode reduces the output voltage, which in turn reduces the system's photoelectric conversion efficiency.

[0010] Fourth, existing freewheeling diodes are installed in junction boxes, which concentrate heat sources, have poor heat dissipation, and are prone to fire hazards.

[0011] There is an urgent need in this field to overcome the aforementioned shortcomings of existing technologies, thereby ensuring the photoelectric conversion efficiency of batteries, improving system safety performance, and reducing battery manufacturing costs.

[0012] It should be noted that this part of the present invention only provides background technology related to the present invention, and does not necessarily constitute prior art or known technology. Summary of the Invention

[0013] To address the technical problems raised in the background section, the present invention is implemented as follows:

[0014] In a first aspect, the present invention provides a structure for a silicon photovoltaic cell in which a Schottky diode MS junction, which is connected in reverse parallel with the pn junction of a photoelectric conversion unit, is integrated in situ on the same substrate silicon wafer.

[0015] This silicon photovoltaic cell includes a substrate silicon wafer having a first silicon region, and a fifth silicon region and a sixth silicon region disposed alternately on the back side of the first silicon region. The fifth silicon region is an ohmic contact region of the first silicon region. The sixth silicon region forms a photoelectric conversion unit pn junction with the first and fifth silicon regions. On the same substrate silicon wafer, a photoelectric conversion unit pn junction and a Schottky diode MS junction are integrated in situ. The Schottky diode MS junction includes a Schottky metal and a second silicon region stacked along the z-axis. Both the Schottky diode MS junction and the photoelectric conversion unit pn junction are disposed on the back side of the first silicon region. The photoelectric conversion unit pn junction is connected in parallel with opposite polarities. The silicon photovoltaic cell has a common electrode led out from the fifth silicon region, an emitter led out from the sixth silicon region, and a freewheeling electrode led out from the Schottky diode MS junction. The common electrode is the common electrode of the photoelectric conversion unit pn junction and the Schottky diode MS junction. The emitter and the freewheeling electrode are ohmically interconnected to form the parallel electrode of the silicon photovoltaic cell. The common electrode and the parallel electrode are the output electrodes of the silicon photovoltaic cell. A third silicon region with the same conductivity type as the first silicon region and an effective impurity concentration more than 5 times higher than that of the first silicon region is disposed between the Schottky diode MS junction and the first silicon region.

[0016] In this invention document, the term "pn junction" includes the pn junction structure and pin junction structure described herein. The term "MS junction" refers to a Schottky barrier junction. The term "Schottky metal" includes metals and metal silicides capable of forming a Schottky barrier junction with the second silicon region.

[0017] In this invention document, the term "common electrode" refers to the common electrode of the photoelectric conversion unit and the Schottky diode, specifically the electrode led out from the first silicon region of the substrate silicon wafer by the fifth silicon region of the same conductivity type through an ohmic contact metal; the term "emitter" refers to the other electrode in the pn junction of the photoelectric conversion unit besides the common electrode, and the emitter is led out from the sixth silicon region through an ohmic contact metal; the term "freewheeling electrode" refers to the other electrode of the Schottky diode besides the common electrode, and the freewheeling electrode is led out from the Schottky metal or the second silicon region through an ohmic contact metal.

[0018] In this invention document, the term "parallel connection of the Schottky diode MS junction and the photoelectric conversion unit pn junction in opposite polarities" refers to a parallel connection where the positive terminal of the Schottky diode MS junction is connected to the negative terminal of the photoelectric conversion unit pn junction, and simultaneously, the negative terminal of the Schottky diode MS junction is connected to the positive terminal of the photoelectric conversion unit pn junction.

[0019] In this invention document, the terms "back side of silicon photovoltaic cell", "back side of first silicon region", and "back side of photoelectric conversion unit" are all the same concept, referring to the side of silicon photovoltaic cell that is opposite to the main light-receiving surface.

[0020] The beneficial effects of this structure are as follows: First, it achieves in-situ hot spot freewheeling protection for silicon photovoltaic cells using an integrated Schottky diode MS junction, eliminating the need for cross-protection provided by complementary cells and requiring no external freewheeling diode, thus providing precise freewheeling protection for a single faulty cell. Second, it leverages the low forward voltage of the Schottky diode MS junction, reducing power loss in hot spot protection. Third, since the reverse voltage across each Schottky diode MS junction is limited to the output voltage of a single photoelectric conversion unit pn junction, with a maximum voltage below 0.8V, the reverse leakage current is small. Fourth, both the Schottky diode MS junction and the photoelectric conversion unit pn junction are located on the back side of the first silicon region of the silicon photovoltaic cell, without occupying the cell's light-receiving area.

[0021] Furthermore, a third silicon region with the same conductivity type as the first silicon region and an effective impurity concentration more than five times higher than that of the first silicon region is disposed between the Schottky diode MS junction and the first silicon region. The beneficial effect is that the high-low potential barrier junction formed between the third silicon region and the first silicon region helps to block the diffusion loss of photogenerated minority carriers generated in the first silicon region to the Schottky diode MS junction region, increasing the output current and thus improving the photoelectric conversion efficiency.

[0022] Preferably, the thickness of the third silicon region in the z-axis direction is greater than 40 nm.

[0023] Furthermore, the effective impurity concentration in the second silicon region of the silicon photovoltaic cell of the present invention is 3 × 10⁻⁶. 17 / cm 3 ~8×10 17 / cm 3 The thickness of the second silicon region in the z-axis direction is greater than 50 nm; or, the effective impurity concentration of the second silicon region is 5 × 10⁻⁶. 16 / cm 3 ~2.5×10 17 / cm 3 The thickness of the second silicon region in the z-axis direction is greater than 160 nm.

[0024] The high effective impurity concentration in the second silicon region, which is different from that in the prior art, is due to the reverse parallel connection of the Schottky diode MS junction and the photoelectric conversion unit pn junction. This limits the reverse voltage that the Schottky diode MS junction can withstand to within 0.8V, which helps to reduce conduction resistance, save process time and power consumption, and reduce process costs.

[0025] Furthermore, in the silicon photovoltaic cell of the present invention, depending on the different polarity requirements of the Schottky diode MS junction, the second silicon region or the Schottky metal can be used to achieve ohmic contact with the third silicon region. Correspondingly, the freewheeling electrode of the silicon photovoltaic cell can be one end of the Schottky metal or one end of the second silicon region.

[0026] Furthermore, in the silicon photovoltaic cell of the present invention, the second, third, fourth, fifth, and sixth silicon regions are formed of silicon materials in at least one of the following forms: amorphous silicon, nano-silicon, microcrystalline silicon, polycrystalline silicon, and monocrystalline silicon, while the first silicon region is formed of silicon materials in at least one of the following forms: polycrystalline silicon or monocrystalline silicon. Its advantage is that it is compatible with XBC type silicon photovoltaic cell processes such as IBC and HBC.

[0027] In some preferred embodiments, the silicon photovoltaic cell of the present invention further includes the following structural features:

[0028] Structure 1: The Schottky diode MS junction and the photoelectric conversion unit pn junction extend in a linear fashion along the y-axis direction on the back side, and are arranged parallel and spaced apart along the x-axis direction on the back side. The aspect ratio of the Schottky diode MS junction in the xy-plane region is greater than 50.

[0029] Its beneficial effects are that, compared with the existing technology patent CN110165006B (which has a small perimeter-to-area ratio of the integrated bypass diode pn junction, a large conduction resistance, and causes additional power loss), the present invention increases the perimeter-to-area ratio of the Schottky diode MS junction, reduces the conduction resistance, and reduces current density stress and thermal stress; it is also easier to interconnect with the photoelectric conversion unit.

[0030] In structure two, the third silicon region is adjacent to the fifth silicon region, which has the same conductivity type as the third silicon region. This is beneficial for reducing the barrier voltage drop of the freewheeling circuit and for reducing the conduction resistance of the Schottky diode MS junction.

[0031] In this invention document, "adjacent" means that there are no materials with significantly different third-phase electrical properties between the two.

[0032] Structure 3 has a second i-silicon layer with a thickness of less than 10nm between the first silicon region and the third silicon region, which helps to reduce the reverse leakage current of the Schottky diode MS junction and facilitates compatibility with HBC battery technology.

[0033] Structure 4 has a first i-silicon layer between the first silicon region and the fifth or sixth silicon region, which is beneficial for compatibility with HBC battery technology;

[0034] Structure 5: On the outermost layer of the back of the silicon photovoltaic cell with continuous current protection function, a barrier dielectric layer with a thickness greater than 100nm is provided. Interconnection windows of the cell are left at the positions of the common electrode and the parallel electrode in the barrier dielectric layer, which helps to improve the ability of the silicon photovoltaic cell electrode system to resist water vapor erosion.

[0035] Existing HBC silicon photovoltaic cells have large exposed electrodes, making them highly sensitive to moisture environments. Moisture corrosion can degrade cell performance, necessitating double-glass encapsulation of the photovoltaic module. This increases the module's weight and raises the construction cost of both the module and the power station. Reducing the glass thickness, however, poses safety hazards. This invention addresses this by adding a barrier dielectric layer, where all metallized circuitry is located on the back of the silicon photovoltaic cell. Furthermore, the low surface roughness of the metallized circuitry allows for the addition of a barrier dielectric layer, improving the moisture barrier effect of the silicon photovoltaic cell. This also facilitates the optimization and selection of different Schottky metals and circuit metals.

[0036] Structure 6: The fifth silicon region, the sixth silicon region, and the optional second silicon region of the battery are respectively provided with a first ohmic contact metal, a second ohmic contact metal, and a third ohmic contact metal on the z-axis direction surface. The main components of the first ohmic contact metal, the second ohmic contact metal, the third ohmic contact metal, and the Schottky metal are aluminum.

[0037] The advantages of using aluminum are its low contact resistance and suitability for forming Schottky or ohmic contacts with both n-type and p-type silicon. Its disadvantage is its susceptibility to corrosion, which can be overcome by adding a barrier dielectric layer. Depositing a barrier dielectric layer creates the conditions for using aluminum in metallized circuitry; simultaneously, the dense and flat nature of the aluminum metallization system makes it possible to deposit the barrier dielectric layer.

[0038] Furthermore, existing battery technologies require brazing interconnects for the electrodes, resulting in high silver consumption. To address this, the present invention solves this problem by using metallized electrodes primarily composed of aluminum, interconnecting individual cells via pressure welding. This approach is more conducive to conserving precious metal resources and reducing the cost of photovoltaic cells.

[0039] In this invention, silicon materials are defined using "p", "n", and "i" to distinguish their conductivity types. The silicon material can be monocrystalline silicon, polycrystalline silicon, microcrystalline silicon, nanocrystalline silicon, or amorphous silicon, the same as the materials used in existing battery technologies. + With p (or n) + The effective impurity concentration of silicon materials adjacent to (n) is relative, and the values ​​can differ by more than 5 times; "i-silicon" refers to intrinsic silicon, but it is not truly silicon free of any p-type or n-type impurities. It only indicates that its effective impurity concentration is very low, a typical value being its resistivity at... On the order of Ω·cm and above.

[0040] In this invention, the doped junction depth of the third silicon region refers to the distance along the z-axis of the region where the effective impurity concentration is more than 5 times higher than that of the first silicon region.

[0041] Unless otherwise specified, the pn junction or pin structure mentioned in this invention is a general term and does not limit its arrangement direction or the impurity concentration at both ends of the junction.

[0042] In this invention, IBC structure refers to the comb-shaped back contact electrode structure of crystalline silicon photovoltaic cells; HBC structure refers to the comb-shaped back contact electrode structure of HJT silicon photovoltaic cells; and XBC refers to the comb-shaped back contact electrode structure of other silicon photovoltaic cells.

[0043] In some specific embodiments of the present invention, a third ohmic contact metal is provided between the second silicon region and the third silicon region, the third ohmic contact metal being in ohmic contact with both the second silicon region and the third silicon region, and the Schottky metal being located on the upper surface of the second silicon region in the z-axis direction, with a freewheeling electrode led out from the Schottky metal.

[0044] In some other specific embodiments of the present invention, a Schottky metal is disposed between the second silicon region and the third silicon region. The Schottky metal is in ohmic contact with the third silicon region and in Schottky barrier rectifier contact with the second silicon region. A third ohmic contact metal is disposed on the upper surface of the second silicon region along the z-axis, and a freewheeling electrode is led out from the third ohmic contact metal.

[0045] Preferably, in the z-axis direction, the effective impurity concentration of the third silicon region increases from bottom to top, and the effective impurity concentration of the second silicon region increases along the direction away from the Schottky metal.

[0046] In this invention, the Schottky diode is a Schottky barrier diode.

[0047] Secondly, the present invention provides two methods for manufacturing silicon photovoltaic cells with freewheeling protection function, both of which include fabricating a freewheeling Schottky diode MS junction and a photoelectric conversion unit pn junction on the back side of a substrate silicon wafer, and connecting the Schottky diode MS junction and the photoelectric conversion unit pn junction in parallel with opposite polarities.

[0048] Method 1:

[0049] The fabrication of the MS junction in a freewheeling Schottky diode includes the following steps:

[0050] S1, Fabricate the isolation high-low barrier junction located between the Schottky diode MS junction and the first silicon region:

[0051] The substrate silicon wafer is a first silicon region. A third silicon region with the same conductivity type as the first silicon region is prepared by doping in a predetermined area on the back side of the substrate silicon wafer. The effective impurity concentration of the third silicon region is more than 5 times higher than that of the first silicon region. The thickness of the third silicon region in the z-axis direction is greater than 50 nm. A p-type interphase (p-type interphase) is formed between the third silicon region and the first silicon region. + p or n + The high and low potential barriers of n.

[0052] In order to achieve good ohmic contact in step S2, existing techniques can be adopted to form a sufficiently high effective surface impurity concentration on the surface in the z-axis direction of the third silicon region.

[0053] S2, Fabrication of the Schottky diode MS junction, including two methods: S2-1 or S2-2:

[0054] S2-1, a Schottky metal layer is deposited on a predetermined region on the upper surface of the third silicon region in the z-axis direction obtained in step S1. A second silicon region is deposited on a predetermined region on the upper surface of the Schottky metal layer in the z-axis direction. A third ohmic contact metal is deposited on a predetermined region on the upper surface of the second silicon region in the z-axis direction. After separate metallization after each deposition, or combined metallization after several depositions, an ohmic contact is formed between the third silicon region and the Schottky metal, a Schottky diode MS junction is formed between the Schottky metal and the second silicon region, and an ohmic contact is formed between the second silicon region and the third ohmic contact metal.

[0055] In order to form a good ohmic contact between the second silicon region and the subsequently fabricated third ohmic contact metal, existing techniques can be used to form a sufficiently high surface doping concentration on the surface of the second silicon region in the z-axis direction.

[0056] In S2-1, a suitable type of Schottky metal and a second silicon region are selected such that, for an n-type second silicon region, the third ohmic contact metal is the negative electrode of the Schottky diode MS junction; and for a p-type second silicon region, the third ohmic contact metal is the positive electrode of the Schottky diode MS junction.

[0057] The third ohmic contact metal mentioned in S2-1 is the freewheeling electrode of the silicon photovoltaic cell.

[0058] In S2-1, the first silicon region is led out through the ohmic contact of the silicon photovoltaic cell and serves as the common electrode of the silicon photovoltaic cell.

[0059] Alternatively, in step S2-2, a third ohmic contact metal is deposited on a predetermined region on the z-axis surface of the third silicon region obtained in step S1, and a second silicon region is deposited on the predetermined region on the z-axis surface of the third ohmic contact metal. Then, Schottky metal is deposited on the predetermined region on the z-axis surface of the second silicon region. After metallization after each deposition, or after merging metallization after several depositions, an ohmic contact is formed between the third silicon region and the third ohmic contact metal, and an ohmic contact is formed between the third ohmic contact metal and the second silicon region. A Schottky diode MS junction is formed between the second silicon region and the Schottky metal.

[0060] In S2-2, a suitable type of Schottky metal and a second silicon region are selected such that, for an n-type second silicon region, its Schottky metal is the positive terminal of the MS junction of a Schottky diode; and for a p-type second silicon region, its Schottky metal is the negative terminal of the MS junction of a Schottky diode.

[0061] The Schottky metal mentioned in S2-2 is the freewheeling electrode of the silicon photovoltaic cell.

[0062] In S2-2, the first silicon region is the common electrode of the silicon photovoltaic cell, which is led out through the ohmic contact of the silicon photovoltaic cell.

[0063] Method 2:

[0064] The fabrication of the MS junction in a freewheeling Schottky diode includes the following steps:

[0065] S1, Fabrication of the high-low barrier junction for isolation between the Schottky diode MS junction and the substrate silicon wafer:

[0066] The substrate silicon wafer is a first silicon region, and a second silicon layer with a thickness of less than 10 nm is prepared in a predetermined area of ​​the first silicon region on the back side of the substrate silicon wafer;

[0067] A third silicon region with the same conductivity type as the first silicon region is deposited in a predetermined region on the surface of the second silicon layer along the z-axis. The effective impurity concentration of the third silicon region is more than 5 times higher than that of the first silicon region, and the deposition thickness of the third silicon region is 40~600nm, so that a p-type interlayer is formed between the third silicon region and the first silicon region. + ip or n + high and low potential barrier junctions in the structure;

[0068] S2, Fabrication of the Schottky diode MS junction, including two methods: S2-1 or S2-2:

[0069] S2-1, a Schottky metal layer is deposited on a predetermined region on the upper surface of the third silicon region in the z-axis direction obtained in step S1. A second silicon region is deposited on a predetermined region on the upper surface of the Schottky metal layer in the z-axis direction. A third ohmic contact metal is deposited on a predetermined region on the upper surface of the second silicon region in the z-axis direction. After separate metallization after each deposition, or combined metallization after several depositions, an ohmic contact is formed between the third silicon region and the Schottky metal, a Schottky diode MS junction is formed between the Schottky metal and the second silicon region, and an ohmic contact is formed between the second silicon region and the third ohmic contact metal.

[0070] The appropriate type of Schottky metal and second silicon region are selected such that, for the n-type second silicon region, the third ohmic contact metal is the negative electrode of the Schottky diode MS junction; and for the p-type second silicon region, the third ohmic contact metal is the positive electrode of the Schottky diode MS junction.

[0071] The third ohmic contact metal is the freewheeling electrode of the silicon photovoltaic cell;

[0072] The first silicon region is led out via an ohmic contact and serves as the common electrode of the silicon photovoltaic cell.

[0073] In order to form a good ohmic contact between the second silicon region and the subsequently fabricated third ohmic contact metal, existing techniques can be used to form a sufficiently high surface doping concentration on the surface of the second silicon region in the z-axis direction.

[0074] In Method 2, S2-2, a third ohmic contact metal is deposited on a preset region on the z-axis surface of the third silicon region obtained in step S1, and a second silicon region is deposited on the preset region on the z-axis surface of the third ohmic contact metal; then, Schottky metal is deposited on the preset region on the z-axis surface of the second silicon region; after metallization after each deposition, or after merging metallization after several depositions, an ohmic contact is formed between the third silicon region and the third ohmic contact metal, an ohmic contact is formed between the third ohmic contact metal and the second silicon region, and a Schottky diode MS junction is formed between the second silicon region and the Schottky metal.

[0075] In order to form a good ohmic contact between the third ohmic contact metal and the third silicon region and the second silicon region respectively, existing technology measures can be adopted, such as forming a sufficiently high surface doping concentration on the upper surface of the third silicon region in the z-axis direction and the lower surface of the second silicon region in the z-axis direction.

[0076] In Method 2, in S2-2, a suitable type of Schottky metal and a second silicon region are selected such that, for the n-type second silicon region, its Schottky metal is the positive electrode of the MS junction of the Schottky diode; and for the p-type second silicon region, its Schottky metal is the negative electrode of the MS junction of the Schottky diode.

[0077] The Schottky metal mentioned in Method 2 S2-2 is the freewheeling electrode of the silicon photovoltaic cell;

[0078] The first silicon region is led out via an ohmic contact and serves as the common electrode of the silicon photovoltaic cell.

[0079] The metallization described in this invention document can be achieved by sintering, annealing or curing. The sintering temperature range is 800℃~500℃, the annealing temperature range is 500℃~200℃, and the curing temperature range is 200℃~room temperature. The lower process temperature is arranged in a later process.

[0080] During, before, or after the preparation of the Schottky diode MS junction in step S2-1 or S2-2 of methods one and two, a fifth and sixth silicon region can be prepared by doping a predetermined region of the first silicon region using existing technology. Alternatively, a first i-silicon layer can be deposited on a predetermined region on the back side of the first silicon region of the substrate silicon wafer using existing technology, and alternating fifth and sixth silicon regions can be deposited on the surface of the first i-silicon layer along the z-axis direction, thereby realizing the preparation of the pn junction of the photoelectric conversion unit. The fifth silicon region has the same conductivity type as the first silicon region and serves as the ohmic contact region of the first silicon region, as well as the ohmic contact region of the common electrode of the silicon photovoltaic cell. The sixth silicon region has a complementary conductivity type to the first silicon region, forming the ohmic contact region of the emitter of the silicon photovoltaic cell.

[0081] To complete the manufacturing of the photovoltaic cell, electrode metallization and connection, and optionally, the fabrication of a barrier dielectric layer, are required as follows:

[0082] Electrode metallization:

[0083] In this invention, "metallization" means that before a certain process (usually sintering, curing or annealing), the circuit as a whole may not exhibit the conductive properties of metal or may not form the required ohmic or rectifier contacts with the silicon of each electrode region. However, after a certain process, the circuit exhibits the conductive properties of metal and forms the required ohmic or rectifier contacts with the silicon of each electrode region, thus forming the terminals of the external circuit.

[0084] Ohmic contact metal is deposited on a predetermined area on the z-axis surface of the fifth silicon region (ohmic contact region of the common electrode), the sixth silicon region (ohmic contact region of the emitter), and the optional second silicon region (ohmic contact region of the freewheeling electrode) formed in step S2, connecting the emitter and the freewheeling electrode. After sintering, annealing, or curing, the metallization of the corresponding ohmic contact metal is completed, forming the common electrode and the parallel electrode of the silicon photovoltaic cell, respectively, and realizing the reverse parallel connection of the Schottky diode MS junction and the photoelectric conversion unit pn junction.

[0085] The phrase "depositing ohmic contact metal in a predetermined area on the upper surface of the second silicon region (ohmic contact region of the freewheeling electrode) along the z-axis" means that, based on actual needs and the battery structure, it can be determined whether to deposit ohmic contact metal in a predetermined area on the upper surface of the second silicon region (ohmic contact region of the freewheeling electrode) along the z-axis. If Schottky metal is located on the upper surface of the second silicon region, then Schottky metal serves as the ohmic contact metal.

[0086] Next, a barrier dielectric layer is prepared according to the requirements for blocking moisture during battery applications:

[0087] On the back side of the silicon photovoltaic cell obtained by the electrode metallization step, i.e. the side on which the metallized electrode system is fabricated, a barrier dielectric layer with a thickness greater than 100 nm is deposited, and at the same time, interconnection windows for cell interconnection are left at the bonding points of the barrier dielectric layer corresponding to the common electrode and the parallel electrode.

[0088] The silicon photovoltaic cells prepared by the two methods described above have the same structure and performance as the silicon photovoltaic cells of the first aspect, and will not be described again here.

[0089] Thirdly, the present invention provides an application of a silicon photovoltaic cell integrating a freewheeling Schottky diode connected in reverse parallel with the pn junction of the photoelectric conversion unit in a photovoltaic module.

[0090] The silicon photovoltaic cell of the present invention is obtained by the structure or manufacturing method of the silicon photovoltaic cell described above.

[0091] Using the aforementioned silicon photovoltaic cells, interconnected via wire bonding and lead-out connections, a photovoltaic module is obtained by encapsulation using existing technology. The freewheeling diode connected externally to the junction box in this photovoltaic module is no longer a necessary component.

[0092] Beneficial effects:

[0093] The present invention provides a silicon photovoltaic cell with freewheeling protection function, its manufacturing method and application, which can realize in-situ freewheeling hot spot protection of a single silicon photovoltaic cell, and has the following beneficial effects:

[0094] First, the in-situ freewheeling protection function of the freewheeling diode photoelectric conversion unit can be realized on the same substrate silicon wafer, without the need for external connection, which simplifies the design and has high reliability.

[0095] Second, the freewheeling diode has a low forward voltage, a large chip perimeter-to-area ratio, low current density, low on-resistance, and good heat dissipation.

[0096] Third, a high-low barrier junction is provided between the MS junction of the freewheeling diode and the substrate silicon wafer to reduce the loss of photogenerated non-equilibrium minority carriers, which is beneficial to maintaining the photoelectric conversion efficiency of silicon photovoltaic cells.

[0097] Fourth, the electrode metallization circuit can use inexpensive metals instead of the existing silver metal, saving silver paste and reducing costs;

[0098] Fifth, the electrode system and ohmic contact system are protected by a barrier dielectric layer, which has a good water vapor barrier effect, improves the waterproof performance of the electrode system, and reduces the cost of photovoltaic module encapsulation and photovoltaic system installation.

[0099] Sixth, the photovoltaic module junction box does not have a freewheeling diode that generates heat, reducing the risk of fire caused by hot spot effect. Attached Figure Description

[0100] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0101] Figure 1 This is a longitudinal sectional view of a silicon photovoltaic cell A with a freewheeling protection function according to Embodiment 1 of the present invention.

[0102] Figure 2 This is a longitudinal sectional view of a silicon photovoltaic cell B with a freewheeling protection function according to Embodiment 2 of the present invention.

[0103] Figure 3 This is a longitudinal sectional view of a silicon photovoltaic cell C with a freewheeling protection function according to Embodiment 3 of the present invention.

[0104] Figure 4 This is a longitudinal sectional view of a silicon photovoltaic cell D with a freewheeling protection function according to Embodiment 4 of the present invention.

[0105] Figure 5 This is a schematic diagram of the electrode distribution, barrier dielectric layer, solder joints, and interconnection windows of a silicon photovoltaic cell with freewheeling protection function according to an embodiment of the present invention.

[0106] Figure 6 This is a schematic diagram of the structure of a photovoltaic module with a freewheeling protection function, formed by connecting silicon photovoltaic cells in series according to the present invention.

[0107] Icons: 100-Silicon photovoltaic cell A; 200-Silicon photovoltaic cell B; 300-Silicon photovoltaic cell C; 400-Silicon photovoltaic cell D; 11-First silicon region; 12-Second silicon region; 13-Third silicon region; 15-Fifth silicon region; 16-Sixth silicon region; 17-First i-silicon layer; 18-Second i-silicon layer; 21-First ohmic contact metal; 22-Second ohmic contact metal; 23-Third ohmic contact metal; 24-Schottky metal; 61-Emitter; 62-Freewheeling electrode; 63-Common electrode; 64-Parallel electrode; 65-Interconnect line; 71-Barrier dielectric layer; 72-Interconnect window. Detailed Implementation

[0108] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0109] The features and performance of the present invention will be further described in detail below with reference to embodiments.

[0110] Example 1

[0111] like Figure 1 , Figure 5 As shown, this embodiment of the invention provides a silicon photovoltaic cell A100 with an n-substrate and HBC structure having a freewheeling protection function. The substrate silicon wafer material is monocrystalline silicon, and its structure includes:

[0112] The interlayer structure of the Schottky diode MS junction, along the z-axis from the substrate silicon wafer to the back of the cell, includes: a first silicon region 11, n-type, with an effective impurity concentration of... / The third silicon region 13, n-type, extends linearly along the y-axis, with an effective impurity concentration of [missing information]. / The thickness is 500 nm, and its upper surface is heavily doped to achieve an effective impurity concentration of . / It is arranged parallel to the fifth silicon region 15 and the sixth silicon region 16. The third silicon region 13 has a width of 0.5 mm in the x-axis direction and a length of 87 mm in the y-axis direction, with an aspect ratio of 174 in the xy-plane region; the third ohmic contact metal 23 has a thickness of 500 nm; the second silicon region 12 is p-type with an effective impurity concentration of... / The thickness is 500 nm, and the lower surface of the second silicon region 12 in the z-axis direction is heavily doped to achieve an effective impurity concentration of [missing value]. / Schottky metal 24, thickness 500nm.

[0113] The photoelectric conversion unit pn junction structure, along the z-axis from the substrate silicon wafer to the back of the cell, includes: a first silicon region 11, n-type, with an effective impurity concentration of... / The first silicon layer 17 is amorphous silicon with a thickness of 3 nm; the fifth silicon region 15 and the sixth silicon region 16 are parallel and alternately arranged linear amorphous silicon materials; a first ohmic contact metal 21 is disposed on the fifth silicon region 15, and a second ohmic contact metal 22 is disposed on the sixth silicon region 16; wherein the fifth silicon region 15 is of n-type conductivity, has a thickness of 500 nm, and an effective impurity concentration / The sixth silicon region 16 has a p-type conductivity, a thickness of 500 nm, and an effective impurity concentration. / .

[0114] Schottky metal 24 is the negative electrode of the MS junction of the Schottky diode; the second silicon region 12 is the positive electrode of the MS junction of the Schottky diode, and its lead is the first ohmic contact metal 21.

[0115] The positive terminal of the pn junction of the photoelectric conversion unit is the second ohmic contact metal 22, and the negative terminal is the first ohmic contact metal 21.

[0116] The main components of the first ohmic contact metal 21, the second ohmic contact metal 22, the third ohmic contact metal 23, and the Schottky metal 24 are all aluminum.

[0117] The fifth silicon region 15, the first i-silicon layer 17, the first silicon region 11, and the sixth silicon region 16 form a pn junction, a photoelectric conversion unit with a pin structure.

[0118] The common electrode 63 of silicon photovoltaic cell A 100; the emitter 61 of silicon photovoltaic cell A 100 is connected to the freewheeling electrode 62, which is the parallel electrode 64 of silicon photovoltaic cell A 100.

[0119] On the outermost layer of the back of the silicon photovoltaic cell A100, there is a barrier dielectric layer 71 made of silicon oxide with a thickness of 100nm. The barrier dielectric layer 71 has interconnection window 72 for interconnecting the cells at the common electrode 63 and the parallel electrode 64.

[0120] The manufacturing method of this embodiment includes the following steps:

[0121] S1, Fabrication of the high-low barrier junction for isolation between the Schottky diode MS junction and the substrate silicon wafer:

[0122] The substrate silicon wafer is n-type, and the effective impurity concentration is / Its technical parameters meet the requirements of HBC silicon photovoltaic cells. On the back side of the substrate silicon wafer, a third silicon region 13 with the same conductivity type as the first silicon region 11 is prepared by local doping in a predetermined region of the first silicon region 11. The effective impurity concentration of the third silicon region 13 is [missing information]. / The junction depth is 500 nm, and the effective impurity concentration on its upper surface reaches [value missing]. / n is formed between the third silicon region 13 and the first silicon region 11. + n High and low potential barrier junction.

[0123] S2, fabricate the Schottky diode MS junction, and interweave to fabricate the photoelectric conversion pn junction:

[0124] A first i-silicon layer 17 of 3 nm is deposited on the back side of the substrate silicon wafer in a predetermined area of ​​the first silicon region 11;

[0125] In the predetermined region on the z-axis direction surface of the third silicon region 13 obtained in step S1, a third ohmic contact metal 23 is deposited;

[0126] A second silicon region 12, p-type, amorphous silicon, is deposited in a predetermined region on the surface of the third ohmic contact metal 23 along the z-axis direction, with an effective impurity concentration. / With a thickness of 500 nm, the effective impurity concentration on the surface in contact with the third ohmic contact metal 23 is... / ;

[0127] A sixth silicon region 16, p-type, is deposited in a predetermined region above the first silicon layer 17, with an effective impurity concentration of [missing information]. / Thickness 500nm;

[0128] A fifth silicon region 15, n-type, is deposited in a predetermined region above the first i-silicon layer 17, with an effective impurity concentration of [missing information]. / Thickness 500nm.

[0129] S3, Electrode metallization connection:

[0130] Schottky metal 24, first ohmic contact metal 21, and second ohmic contact metal 22 are deposited on the predetermined areas of the upper surfaces of the second silicon region 12, the fifth silicon region 15, and the sixth silicon region 16 along the z-axis, respectively. In this embodiment, Schottky metal 24, first ohmic contact metal 21, and second ohmic contact metal 22 are all aluminum. After annealing, ohmic contacts are formed between the third silicon region 13 and the third ohmic contact metal 23, and between the third ohmic contact metal 23 and the second silicon region 12, respectively. A Schottky diode MS junction is formed between the second silicon region 12 and the Schottky metal 24, completing the metallization of the ohmic contact metal and the Schottky metal. This connects the Schottky metal 24 and the second ohmic contact metal 22, forming the parallel electrode 64 of the silicon photovoltaic cell A 100. The first ohmic contact metals 21 are interconnected, forming the common electrode 63 of the silicon photovoltaic cell A 100. This also achieves the reverse parallel connection of the Schottky diode MS junction and the pn junction of the photoelectric conversion unit.

[0131] S4, Preparation of the barrier dielectric layer:

[0132] On the back side of the silicon photovoltaic cell A 100 obtained in step S3, a barrier dielectric layer 71 of silicon oxide with a thickness of 100 nm is deposited, and an interconnection window 72 for interconnecting the cells is left at the bonding joint of the common electrode 63 and the parallel electrode 64 on the barrier dielectric layer 71.

[0133] Example 2

[0134] like Figure 2 , Figure 5 As shown, this embodiment of the invention provides a silicon photovoltaic cell B200 with an n-substrate and HBC structure that has a freewheeling protection function. The substrate silicon wafer material is monocrystalline silicon, and its structure includes:

[0135] The interlayer structure of the Schottky diode MS junction, along the z-axis from the substrate silicon wafer to the back of the cell, includes: a first silicon region 11, n-type, with an effective impurity concentration of... / The third silicon region 13, n-type, extends linearly along the y-axis, with an effective impurity concentration of [missing information]. / The surface heavy doping along the z-axis results in an effective impurity concentration of / It is arranged parallel to the fifth silicon region 15 and the sixth silicon region 16, with an aspect ratio greater than 100 and a thickness of 500 nm in the xy plane; Schottky metal 24, with a thickness of 500 nm; the second silicon region 12, n-type, with an effective impurity concentration of / With a thickness of 500 nm, the effective impurity concentration on the surface along the z-axis is... / The third ohmic contact metal 23 has a thickness of 500 nm.

[0136] The pn junction interlayer structure of the photoelectric conversion unit, along the z-axis from the substrate silicon wafer to the back of the cell, includes: a first silicon region 11, n-type, with an effective impurity concentration of... / The first silicon layer 17 is amorphous silicon with a thickness of 3 nm; the fifth silicon region 15 and the sixth silicon region 16 are amorphous silicon materials that are arranged in parallel and parallel lines along the y-axis; a first ohmic contact metal 21 is disposed on the fifth silicon region 15, and a second ohmic contact metal 22 is disposed on the sixth silicon region 16; wherein the fifth silicon region 15 is of n-type conductivity, has a thickness of 500 nm, and an effective impurity concentration of / The sixth silicon region 16 has a p-type conductivity, a thickness of 500 nm, and an effective impurity concentration. / .

[0137] The third ohmic contact metal 23 is the negative terminal of the Schottky diode MS junction; the Schottky metal 24 is the positive terminal of the Schottky diode MS junction, and the positive terminal is the first ohmic contact metal 21.

[0138] The fifth silicon region 15, the first i-silicon layer 17, the first silicon region 11, and the sixth silicon region 16 form a pn junction, a photoelectric conversion unit with a pin structure.

[0139] The positive terminal of the pn junction of the photoelectric conversion unit is the second ohmic contact metal 22, and the negative terminal is the first ohmic contact metal 21.

[0140] The main components of the first ohmic contact metal 21, the second ohmic contact metal 22, the third ohmic contact metal 23, and the Schottky metal 24 are all aluminum.

[0141] The first ohmic contact metals 21 in the silicon photovoltaic cell B 200 are interconnected to form the common electrode 63 of the silicon photovoltaic cell B 200; the emitter 61 of the silicon photovoltaic cell B 200 is connected to the freewheeling electrode 62 to form the parallel electrode 64 of the silicon photovoltaic cell B 200.

[0142] On the outer layer of the metallized electrode in the z-axis direction on the back side of the silicon photovoltaic cell B 200, a barrier dielectric layer 71 with a thickness of 100nm of silicon oxide is provided. The barrier dielectric layer 71 has interconnection window 72 for interconnecting the cells at the common electrode 63 and the parallel electrode 64.

[0143] The manufacturing method of this embodiment includes the following steps:

[0144] S1, Fabrication of the high-low barrier junction for isolation between the Schottky diode MS junction and the substrate silicon wafer:

[0145] The substrate silicon wafer is n-type, and the effective impurity concentration is / Its technical parameters meet the requirements of HBC silicon photovoltaic cells. On the back side of the substrate silicon wafer, a third silicon region 13 with the same conductivity type as the first silicon region 11 is prepared by local doping in a predetermined region of the first silicon region 11. The effective impurity concentration of the third silicon region 13 is [missing information]. / The junction depth is 500 nm, and the effective impurity concentration on the surface along the z-axis reaches [value missing]. / n is formed between the third silicon region 13 and the first silicon region 11. + n High and low potential barrier junction.

[0146] S2, fabricate the Schottky diode MS junction, and interweave to fabricate the photoelectric conversion pn junction:

[0147] A first i-silicon layer 17 of 3 nm is deposited on the back side of the substrate silicon wafer in a predetermined area of ​​the first silicon region 11;

[0148] Schottky metal 24 is deposited on a predetermined region on the upper surface of the third silicon region 13 in the z-axis direction obtained in step S1;

[0149] A second silicon region 12, n-type, amorphous silicon, is deposited in a predetermined region on the surface of the Schottky metal 24 along the z-axis direction, with an effective impurity concentration. / With a thickness of 500 nm, the effective impurity concentration on the upper surface in contact with the third ohmic contact metal 23 is... / ;

[0150] A sixth silicon region 16, p-type, is deposited in a predetermined region above the first silicon layer 17, with an effective impurity concentration of [missing information]. / Thickness 500nm;

[0151] A fifth silicon region 15, n-type, is deposited in a predetermined region above the first i-silicon layer 17, with an effective impurity concentration of [missing information]. / Thickness 500nm.

[0152] S3, Electrode metallization connection:

[0153] On predetermined areas on the z-axis surfaces of the second silicon region 12, the fifth silicon region 15, and the sixth silicon region 16, a third ohmic contact metal 23, a first ohmic contact metal 21, and a second ohmic contact metal 22 are deposited, respectively. In this embodiment, the third ohmic contact metal 23, the first ohmic contact metal 21, and the second ohmic contact metal 22 are all aluminum. Subsequently, after annealing, ohmic contacts are formed between the third silicon region 13 and the Schottky metal 24, a Schottky diode MS junction is formed between the Schottky metal 24 and the second silicon region 12, an ohmic contact is formed between the second silicon region 12 and the third ohmic contact metal 23, and ohmic contacts are formed between the fifth silicon region 15 and the first ohmic contact metal 21, and between the sixth silicon region 16 and the second ohmic contact metal 22. Simultaneously, the metallization of the ohmic contact metal and the Schottky metal is completed, connecting the third ohmic contact metal 23 with the second ohmic contact metal 22 to form the parallel electrode 64 of the silicon photovoltaic cell B 200. The first ohmic contact metal 21, after interconnection, forms the common electrode 63 of the silicon photovoltaic cell B 200. Furthermore, the Schottky diode MS junction and the photoelectric conversion unit pn junction are connected in reverse parallel.

[0154] S4, Preparation of the barrier dielectric layer:

[0155] On the back side of the silicon photovoltaic cell B 200 obtained in step S3, a silicon oxide barrier dielectric layer 71 with a thickness of 100 nm is deposited; and on the barrier dielectric layer 71, an interconnection window 72 for interconnecting the cells is left at the bonding joint of the common electrode 63 and the parallel electrode 64.

[0156] Example 3

[0157] like Figure 3 , Figure 5As shown, this embodiment of the invention provides a silicon photovoltaic cell C300 with a p-substrate and HBC structure that has a freewheeling protection function. The substrate silicon wafer material is monocrystalline silicon, and its structure includes:

[0158] The interlayer structure of the Schottky diode MS junction, along the z-axis from the substrate silicon wafer to the back of the cell, includes: a first silicon region 11, p-type, with an effective impurity concentration of... / The second silicon layer 18 has a thickness of 3 nm; a linear third silicon region 13 is arranged parallel to the fifth silicon region 15 and the sixth silicon region 16, with an aspect ratio greater than 100 in the xy-plane region, a thickness of 500 nm, p-type, and an effective impurity concentration of [missing information]. / The effective impurity concentration on the surface along the z-axis is / The third ohmic contact metal 23 has a thickness of 500 nm; the second silicon region 12 is n-type with an effective impurity concentration of [missing information]. / With a thickness of 500 nm, the effective impurity concentration on the lower surface along the z-axis is: / Schottky metal 24, thickness 500nm.

[0159] The pn junction interlayer structure of the photoelectric conversion unit, along the z-axis from the substrate silicon wafer to the back of the cell, includes: a first silicon region 11, p-type, with an effective impurity concentration of... / The first silicon layer 17 is amorphous silicon with a thickness of 3 nm; a fifth silicon region 15 and a sixth silicon region 16 of parallel alternating linear amorphous silicon are provided; a first ohmic contact metal 21 is provided on the fifth silicon region 15, and a second ohmic contact metal 22 is provided on the sixth silicon region 16; wherein the fifth silicon region 15 is p-type conductive, has a thickness of 500 nm, and an effective impurity concentration of / The sixth silicon region 16 has an n-type conductivity, a thickness of 500 nm, and an effective impurity concentration. / ;

[0160] Schottky metal 24 is the positive electrode of the MS junction of the Schottky diode; the second silicon region 12 is the negative electrode of the MS junction of the Schottky diode, and its lead-out terminal is the first ohmic contact metal 21;

[0161] The fifth silicon region 15, the first i-silicon layer 17, the first silicon region 11, and the sixth silicon region 16 form a pn junction, a photoelectric conversion unit with a pin structure.

[0162] The negative terminal of the pn junction of the photoelectric conversion unit is the second ohmic contact metal 22, and the positive terminal is the first ohmic contact metal 21.

[0163] In this embodiment, the main components of the first ohmic contact metal 21, the second ohmic contact metal 22, the third ohmic contact metal 23, and the Schottky metal 24 are all aluminum.

[0164] The first ohmic contact metals 21 in the silicon photovoltaic cell C 300 are interconnected to form the common electrode 63 of the silicon photovoltaic cell C 300; the emitter 61 of the silicon photovoltaic cell C 300 is connected to the freewheeling electrode 62 to form the parallel electrode 64 of the silicon photovoltaic cell C 300.

[0165] On the outer layer of the metallized electrode in the z-axis direction on the back side of the silicon photovoltaic cell C300, a barrier dielectric layer 71 with a thickness of 100nm of silicon oxide is provided. The barrier dielectric layer 71 has interconnection window 72 for interconnecting the cells at the common electrode 63 and the parallel electrode 64.

[0166] The manufacturing method of this embodiment includes the following steps:

[0167] S1, Fabrication of the high-low barrier junction for isolation between the Schottky diode MS junction and the substrate silicon wafer:

[0168] The substrate silicon wafer is p-type, and the effective impurity concentration is [missing information]. / Its technical parameters meet the requirements of HBC silicon photovoltaic cells. On the back side of the substrate silicon wafer, a second i-silicon layer 18 and a first i-silicon layer 17 with a thickness of 3 nm are deposited in a predetermined region of the first i-silicon region 11. A third silicon region 13 with the same conductivity type as the first silicon region 11 and a thickness of 500 nm are deposited in a predetermined region on the surface of the second i-silicon layer 18 in the z-axis direction. The effective impurity concentration of the third silicon region 13 is [missing information]. / And the effective impurity concentration on its upper surface reaches / p is formed between the third silicon region 13 and the first silicon region 11. + High and low potential barrier junctions in IP structure;

[0169] A sixth silicon region 16, n-type, is deposited in a predetermined region on the surface of the first i-silicon layer 17 along the z-axis direction, with an effective impurity concentration of [missing information]. / The thickness is 500 nm; a fifth silicon region 15, p-type, is deposited in a predetermined area above the first i-silicon layer 17, with an effective impurity concentration of [missing information]. / With a thickness of 500nm, a pn junction is formed to form the pin structure of the photoelectric conversion unit.

[0170] S2, Fabrication of the MS junction silicon region of the Schottky diode:

[0171] A third ohmic contact metal 23 with a thickness of 500 nm is deposited in a predetermined region above the third silicon region 13 in the z-axis direction obtained in step S1. A second silicon region 12 (n-type, amorphous silicon, effective impurity concentration) is deposited in a predetermined region above the third ohmic contact metal 23 in the z-axis direction. / With a thickness of 500 nm, the effective impurity concentration on the lower surface of the second silicon region along the z-axis is [value missing]. / .

[0172] S3, Electrode metallization connection:

[0173] Schottky metal 24, first ohmic contact metal 21, and second ohmic contact metal 22 are deposited on predetermined regions on the z-axis surfaces of the second silicon region 12, the fifth silicon region 15, and the sixth silicon region 16, respectively. Following an annealing process, ohmic contacts are formed between the third silicon region 13 and the third ohmic contact metal 23, between the third ohmic contact metal 23 and the second silicon region 12, and between the second silicon region 12 and the Schottky metal 24. Ohmic contacts are also formed between the fifth silicon region 15 and the first ohmic contact metal 21, and between the sixth silicon region 16 and the second ohmic contact metal 22. Simultaneously, the ohmic contact metals and the Schottky metal are metallized, connecting the Schottky metal 24 and the second ohmic contact metal 22 to form the parallel electrode 64 of the silicon photovoltaic cell C 300. The first ohmic contact metals 21 are interconnected to form the common electrode 63 of the silicon photovoltaic cell C 300. And achieves reverse parallel connection between the Schottky diode MS junction and the photoelectric conversion unit pn junction.

[0174] S4, Preparation of the barrier dielectric layer:

[0175] On the back side of the silicon photovoltaic cell C 300 obtained in step S3, a silicon oxide barrier dielectric layer 71 with a thickness of 100 nm is deposited, and an interconnection window 72 for interconnecting the cells is left at the bonding joint of the common electrode 63 and the parallel electrode 64 on the barrier dielectric layer 71.

[0176] Example 4

[0177] like Figure 4 , Figure 5 As shown, this embodiment of the invention provides a silicon photovoltaic cell D400 with a p-substrate, an IBC structure integrating a Schottky diode MS junction, and the substrate silicon wafer material is monocrystalline silicon. Its structure includes:

[0178] The interlayer structure of the Schottky diode MS junction, along the z-axis from the substrate silicon wafer to the back of the cell, includes: a first silicon region 11, p-type, with an effective impurity concentration of... / The linear third silicon region 13, arranged parallel to the fifth silicon region 15 and the sixth silicon region 16, has an aspect ratio greater than 100 in the xy-plane region, is p-type, and has an effective impurity concentration of [missing information]. / The junction depth is 500 nm, and the effective impurity concentration on the upper surface of the third silicon region 13 is [missing information]. / Schottky metal 24, thickness 500nm; Second silicon region 12, p-type, effective impurity concentration is... / With a thickness of 500 nm, the effective impurity concentration on the surface along the z-axis is... / The third ohmic contact metal 23 has a thickness of 500 nm.

[0179] The photoelectric conversion unit pn junction structure, along the z-axis from the substrate silicon wafer to the back of the cell, includes: a first silicon region 11, p-type, with an effective impurity concentration of... / Parallel alternating linear fifth silicon regions 15 and sixth silicon regions 16; a first ohmic contact metal 21 is disposed on the fifth silicon region 15, and a second ohmic contact metal 22 is disposed on the sixth silicon region 16; wherein the fifth silicon region 15 is p-type, with a junction depth of 500 nm and an effective impurity concentration of / The sixth silicon region 16 has an n-type conductivity, a junction depth of 500 nm, and an effective impurity concentration. / ;

[0180] The third silicon region 13 is adjacent to part of the fifth silicon region 15, which helps to reduce the barrier voltage drop of the freewheeling circuit and the conduction resistance of the Schottky diode MS junction.

[0181] The third ohmic contact metal 23 is the positive terminal of the Schottky diode MS junction; the Schottky metal 24 is the negative terminal of the Schottky diode MS junction, and its lead-out terminal is the first ohmic contact metal 21;

[0182] The fifth silicon region 15, the first silicon region 11, and the sixth silicon region 16 form a pn junction, a photoelectric conversion unit.

[0183] The negative terminal of the pn junction of the photoelectric conversion unit is the second ohmic contact metal 22, and the positive terminal is the first ohmic contact metal 21.

[0184] In this embodiment, the main components of the first ohmic contact metal 21, the second ohmic contact metal 22, the third ohmic contact metal 23, and the Schottky metal 24 are all aluminum.

[0185] The first ohmic contact metals 21 interconnected in the silicon photovoltaic cell D 400 are the common electrode 63 of the silicon photovoltaic cell D 400; the emitter 61 of the silicon photovoltaic cell D 400 is connected to the freewheeling electrode 62 to form the parallel electrode 64 of the silicon photovoltaic cell D 400.

[0186] On the outer layer of the metallized electrode in the z-axis direction on the back side of the silicon photovoltaic cell D 400, a barrier dielectric layer 71 with a thickness of 100 nm of silicon oxide is provided. The barrier dielectric layer 71 has interconnection window 72 for interconnecting the cells at the common electrode 63 and the parallel electrode 64.

[0187] The manufacturing method of this embodiment includes the following steps:

[0188] S1, Fabrication of an isolation high-low barrier junction located between the Schottky diode MS junction and the substrate silicon wafer:

[0189] The substrate silicon wafer is p-type, and the effective impurity concentration is [missing information]. / Its technical parameters meet the requirements of IBC silicon photovoltaic cells. On the back side of the substrate silicon wafer, a third silicon region 13 with the same conductivity type as the first silicon region 11 is prepared by local doping in a predetermined region of the first silicon region 11, and a p-type matrix is ​​formed between the third silicon region 13 and the first silicon region 11. + p-high and low potential barrier junction.

[0190] Meanwhile, on the back side of the substrate silicon wafer, a fifth silicon region 15 and a sixth silicon region 16 are formed by local doping in a predetermined area of ​​the first silicon region 11.

[0191] S2, Fabrication of the Schottky diode MS junction:

[0192] Schottky metal 24 with a thickness of 500 nm is deposited on the predetermined region on the upper surface of the third silicon region 13 in the z-axis direction obtained in step S1.

[0193] A second silicon region 12, p-type, amorphous silicon, is deposited in a predetermined region on the surface of the Schottky metal 24 along the z-axis direction, with an effective impurity concentration. / With a thickness of 500 nm, the effective impurity concentration on its upper surface is... / cm 3 ;

[0194] S3, Electrode metallization connection:

[0195] On predetermined areas on the z-axis surfaces of the second silicon region 12, the fifth silicon region 15, and the sixth silicon region 16, a third ohmic contact metal 23, a first ohmic contact metal 21, and a second ohmic contact metal 22 are deposited, respectively. In this embodiment, the third ohmic contact metal 23, the first ohmic contact metal 21, and the second ohmic contact metal 22 are all aluminum. Subsequently, after annealing, ohmic contacts are formed between the third silicon region 13 and the Schottky metal 24, a Schottky diode MS junction is formed between the Schottky metal 24 and the second silicon region 12, an ohmic contact is formed between the second silicon region 12 and the third ohmic contact metal 23, and ohmic contacts are formed between the fifth silicon region 15 and the first ohmic contact metal 21, and between the sixth silicon region 16 and the second ohmic contact metal 22. Simultaneously, the metallization of the ohmic contact metal and the Schottky metal is completed, connecting the third ohmic contact metal 23 and the second ohmic contact metal 22 to form the parallel electrode 64 of the silicon photovoltaic cell D 400; the first ohmic contact metal 21 are interconnected to form the common electrode 63 of the silicon photovoltaic cell D 400. Furthermore, the Schottky diode MS junction and the photoelectric conversion unit pn junction are connected in reverse parallel.

[0196] S4, Preparation of the barrier dielectric layer:

[0197] On the back side of the silicon photovoltaic cell D 400 obtained in step S3, a silicon oxide barrier dielectric layer 71 with a thickness of 100 nm is deposited; and on the barrier dielectric layer 71, interconnection window 72 for interconnecting the cells is left at the bonding positions of the common electrode 63 and the parallel electrode 64.

[0198] A photovoltaic module with freewheeling protection function formed by connecting silicon photovoltaic cells in series according to the present invention is shown below. Figure 6 As shown, it can be connected via interconnect window 72 and interconnect line 65.

Claims

1. A silicon photovoltaic cell with a freewheeling protection function, comprising a substrate silicon wafer having a first silicon region, a fifth silicon region and a sixth silicon region arranged on the back of the first silicon region and arranged alternately, wherein the fifth silicon region is an ohmic contact region of the first silicon region, and the sixth silicon region forms a photoelectric conversion unit pn junction with the first silicon region and the fifth silicon region, characterized in that: On the same substrate silicon wafer, a photoelectric conversion unit pn junction and a Schottky diode MS junction are in-situ integrated, the Schottky diode MS junction includes a Schottky metal and a second silicon region stacked in a z-axis direction, the Schottky diode MS junction and the photoelectric conversion unit pn junction are both arranged on the back of the first silicon region, the Schottky diode MS junction and the photoelectric conversion unit pn junction are in a parallel state with reverse polarity, the silicon photovoltaic cell has a common electrode led out from the fifth silicon region, an emitter led out from the sixth silicon region, and a freewheeling electrode led out from the Schottky diode MS junction, the common electrode is a common electrode of the photoelectric conversion unit pn junction and the Schottky diode MS junction, the emitter and the freewheeling electrode are ohmically interconnected to form a parallel electrode of the silicon photovoltaic cell, and the common electrode and the parallel electrode are output electrodes of the silicon photovoltaic cell; a third silicon region with the same conductivity type as the first silicon region and an effective impurity concentration more than 5 times higher than that of the first silicon region is arranged between the Schottky diode MS junction and the first silicon region.

2. The silicon photovoltaic cell with freewheeling protection function according to claim 1, characterized in that: The thickness of the third silicon region in the z-axis direction is greater than 40 nm.

3. The silicon photovoltaic cell with freewheeling protection function according to claim 1, characterized in that: The effective impurity concentration of the second silicon region is 3×10 17 / cm 3 ~8×10 17 / cm 3 , the thickness of the second silicon region in the z-axis direction is greater than 50 nm; or, The effective impurity concentration of the second silicon region is 5×10 16 / cm 3 ~3×10 17 / cm 3 , the thickness of the second silicon region in the z-axis direction is greater than 160nm.

4. The silicon photovoltaic cell with freewheeling protection function according to claim 1, characterized in that: A third ohmic contact metal is disposed between the second silicon region and the third silicon region, the third ohmic contact metal is in ohmic contact with the second silicon region and the third silicon region at the same time, the Schottky metal is located on the upper surface of the second silicon region in the z-axis direction, and the freewheeling electrode is led out by the Schottky metal; or, A Schottky metal is arranged between the second silicon region and the third silicon region, the Schottky metal is in ohmic contact with the third silicon region and in Schottky barrier rectifying contact with the second silicon region, a third ohmic contact metal is arranged on the upper surface of the second silicon region in the z-axis direction, and a freewheeling electrode is led out from the third ohmic contact metal.

5. The silicon photovoltaic cell with freewheeling protection function according to claim 1, characterized in that: The second silicon region, the third silicon region, the fourth silicon region, the fifth silicon region, and the sixth silicon region are each independently formed of at least one form of silicon material among amorphous silicon, nano silicon, microcrystalline silicon, and crystalline silicon, and the first silicon region is formed of crystalline silicon material.

6. The silicon photovoltaic cell with freewheeling protection function according to any one of claims 1 to 5, characterized in that: The silicon photovoltaic cell further comprises a structure having at least one of the following features: Structure 1: the Schottky diode MS junction and the photoelectric conversion unit pn junction extend linearly along the y-axis direction of the back side, are arranged in parallel and spaced apart along the x-axis direction of the back side, and the aspect ratio of the Schottky diode MS junction in the xy plane area is greater than 50; Structure 2, the third silicon region is adjacent to a portion of the fifth silicon region having the same conductivity type as the third silicon region; Structure three, a second i silicon layer with a thickness of less than 10 nm is provided between the first silicon region and the third silicon region; Structure 4, a first i silicon layer is provided between the first silicon region and the fifth silicon region or the sixth silicon region; Structure 5: A barrier dielectric layer with a thickness greater than 100 nm is provided on the outermost layer on the back of the silicon photovoltaic cell, and a cell interconnection line window is left at the position of the barrier dielectric layer corresponding to the common electrode and the parallel electrode; Structure six: The upper surfaces of the fifth silicon region and the sixth silicon region in the z-axis direction are respectively provided with a first ohmic contact metal and a second ohmic contact metal, and the first ohmic contact metal, the second ohmic contact metal, the third ohmic contact metal and the Schottky metal are made of metal aluminum.

7. A method for manufacturing a silicon photovoltaic cell with a freewheeling protection function, characterized in that: The method comprises preparing a freewheeling Schottky diode MS junction and a photoelectric conversion unit pn junction on the back of a substrate silicon wafer, and connecting the Schottky diode MS junction and the photoelectric conversion unit pn junction in parallel with reverse polarity, wherein the preparation of the freewheeling Schottky diode MS junction comprises the following steps: S1, preparing an isolation high-low barrier junction between the Schottky diode MS junction and the first silicon region: The substrate silicon wafer is a first silicon region, and a third silicon region of the same conductivity type as the first silicon region is prepared by doping in a preset region of the first silicon region on the back of the substrate silicon wafer, the effective impurity concentration of the third silicon region is more than 5 times higher than the effective impurity concentration of the first silicon region, the thickness of the third silicon region in the z-axis direction is greater than 50nm, and a p is formed between the third silicon region and the first silicon region + p or n + n's high and low potential barriers; S2, preparation of Schottky diode MS junction, including S2-1 or S2-2 methods: S2-1, depositing a Schottky metal layer on a preset area on the upper surface of the third silicon region in the z-axis direction obtained in step S1, depositing a second silicon region on a predetermined area on the upper surface of the Schottky metal layer in the z-axis direction, depositing a third ohmic contact metal on a predetermined area on the upper surface of the second silicon region in the z-axis direction, and forming an ohmic contact between the third silicon region and the Schottky metal, a Schottky diode MS junction between the Schottky metal and the second silicon region, and an ohmic contact between the second silicon region and the third ohmic contact metal after separate metallization after each deposition or combined metallization after several depositions, respectively; The Schottky metal and the second silicon region are selected so that for the n-type second silicon region, the third ohmic contact metal is the cathode of the Schottky diode MS junction; and for the p-type second silicon region, the third ohmic contact metal is the anode of the Schottky diode MS junction; The third ohmic contact metal is the freewheeling electrode of the silicon photovoltaic cell; The first silicon region is led out through an ohmic contact and is the common pole of the silicon photovoltaic cell; S2-2, depositing a third ohmic contact metal on a preset area on the upper surface of the third silicon region in the z-axis direction obtained in step S1, depositing a second silicon region on a preset area on the upper surface of the third ohmic contact metal in the z-axis direction, and then depositing a Schottky metal on a preset area on the upper surface of the second silicon region in the z-axis direction, and after metallization after each deposition, or combined metallization after several depositions, respectively forming an ohmic contact between the third silicon region and the third ohmic contact metal, and forming an ohmic contact between the third ohmic contact metal and the second silicon region, and forming a Schottky diode MS junction between the second silicon region and the Schottky metal; wherein the Schottky metal and the second silicon region are selected such that, for the n-type second silicon region, the Schottky metal thereof is the positive electrode of the Schottky diode MS junction; and for the p-type second silicon region, the Schottky metal thereof is the negative electrode of the Schottky diode MS junction; The Schottky metal is the freewheeling electrode of the silicon photovoltaic cell; The first silicon region is led out through an ohmic contact and serves as the common pole of the silicon photovoltaic cell.

8. A method for manufacturing a silicon photovoltaic cell with a freewheeling protection function, characterized in that: The method comprises preparing a freewheeling Schottky diode MS junction and a photoelectric conversion unit pn junction on the back of a substrate silicon wafer, and connecting the Schottky diode MS junction and the photoelectric conversion unit pn junction in parallel with reverse polarity, wherein the preparation of the freewheeling Schottky diode MS junction comprises the following steps: S1, prepare the isolation high and low barrier junction between the Schottky diode MS junction and the substrate silicon wafer: The substrate silicon wafer is a first silicon region, and a second i silicon layer with a thickness of less than 10 nm is prepared in a preset region of the first silicon region on the back side of the substrate silicon wafer; A third silicon region of the same conductivity type as the first silicon region is deposited in a preset region on the surface of the second silicon layer in the z-axis direction, wherein the effective impurity concentration of the third silicon region is more than 5 times higher than the effective impurity concentration of the first silicon region, and the deposition thickness of the third silicon region is 40-600 nm, so that a p-type gap is formed between the third silicon region and the first silicon region. + ip or n + in structure of high and low potential barrier junction; S2, preparation of Schottky diode MS junction, including S2-1 or S2-2 methods: S2-1, depositing a Schottky metal layer on a preset area on the upper surface of the third silicon region in the z-axis direction obtained in step S1, depositing a second silicon region on a predetermined area on the upper surface of the Schottky metal layer in the z-axis direction, depositing a third ohmic contact metal on a predetermined area on the upper surface of the second silicon region in the z-axis direction, and forming an ohmic contact between the third silicon region and the Schottky metal, a Schottky diode MS junction between the Schottky metal and the second silicon region, and an ohmic contact between the second silicon region and the third ohmic contact metal after separate metallization after each deposition or combined metallization after several depositions; The Schottky metal and the second silicon region are selected so that for the n-type second silicon region, the third ohmic contact metal is the cathode of the Schottky diode MS junction; and for the p-type second silicon region, the third ohmic contact metal is the anode of the Schottky diode MS junction; The third ohmic contact metal is the freewheeling electrode of the silicon photovoltaic cell; The first silicon region is led out through an ohmic contact and is the common pole of the silicon photovoltaic cell; S2-2, depositing a third ohmic contact metal on a preset area on the upper surface of the third silicon region in the z-axis direction obtained in step S1, and depositing a second silicon region on a preset area on the upper surface of the third ohmic contact metal in the z-axis direction; Then, depositing Schottky metal on a preset area on the surface of the second silicon region in the z-axis direction; After metallization after each deposition, or after combined metallization after several depositions, an ohmic contact is formed between the third silicon region and the third ohmic contact metal, an ohmic contact is formed between the third ohmic contact metal and the second silicon region, and a Schottky diode MS junction is formed between the second silicon region and the Schottky metal; wherein the Schottky metal and the second silicon region are selected such that, for the n-type second silicon region, the Schottky metal thereof is the positive electrode of the Schottky diode MS junction; and for the p-type second silicon region, the Schottky metal thereof is the negative electrode of the Schottky diode MS junction; The Schottky metal is the freewheeling electrode of the silicon photovoltaic cell; The first silicon region is led out through an ohmic contact and serves as the common pole of the silicon photovoltaic cell.

9. A silicon photovoltaic cell with a freewheeling protection function, characterized in that: The silicon photovoltaic cell is integrated with a freewheeling Schottky diode and is obtained by the method for manufacturing a silicon photovoltaic cell integrated with a freewheeling Schottky diode as claimed in claim 7 or 8.

10. A photovoltaic module, characterized in that: It comprises the silicon photovoltaic cell with a follow-up protection function as claimed in any one of claims 1 to 6, or comprises the silicon photovoltaic cell with a follow-up protection function as claimed in claim 9.

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