P-type TBC solar cell and manufacturing method therefor

Abstract

A P-type TBC solar cell and a manufacturing method therefor. The P-type TBC solar cell comprises P-type substrate silicon, wherein the backside of the P-type substrate silicon comprises a patterned N-type region; in the N-type region, a first tunneling layer, an N-type polysilicon layer, a first conductive shielding layer, a first passivation anti-reflection layer and a non-silver N fine finger are sequentially disposed outwards from the backside of the P-type substrate silicon; and the non-silver N fine finger penetrates the first passivation anti-reflection layer to come into contact with the first conductive shielding layer. In the present invention, a non-silver N fine finger is used as a metal electrode in an N-type region of the back face of a cell, such that the production costs of a P-type TBC solar cell can be greatly reduced; moreover, by means of providing a conductive shielding layer between the non-silver N fine finger and a corresponding polysilicon, metal slurry is prevented from coming into direct contact with the polysilicon during sintering of the non-silver N fine finger, such that the contact resistance is greatly reduced, fill factors of the cell are increased, an open-circuit voltage of the cell is increased and the photoelectric conversion efficiency of the cell is improved.

Description

A P-type TBC solar cell and its manufacturing method

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on January 11, 2024, with application number 202410050057.6 and invention name “A P-type TBC solar cell and its manufacturing method”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present invention relates to the field of photovoltaic power generation, and in particular to a P-type TBC solar cell and a manufacturing method thereof. Background Art

[0003] With the continuous development of solar cells, the research and development and manufacture of efficient, stable and low-cost solar cells are the focus of current industry attention. Compared with P-type crystalline silicon cells, N-type crystalline silicon cells have a long minority carrier lifetime, no photodegradation, good low-light effect and small temperature coefficient, which is the hope for crystalline silicon solar cells to reach the theoretical highest efficiency.

[0004] TBC (Tunneling oxide passivated Back Contact) solar cells refer to a back-junction, back-contact solar cell structure in which the positive and negative metal electrodes are arranged in an interdigitated manner on the backlight side of the cell. Its pn junction is located on the back of the cell, using P+ polycrystalline silicon as the emitter (Emitter), doped with N++ as the back surface field (BSF), and a tunneling oxide layer is deposited between the polycrystalline silicon substrate, thereby increasing carrier selectivity, reducing minority carrier recombination, and improving the open circuit voltage of the cell. In addition, since the front surface of the TBC cell is not blocked by a metal electrode, the light incident on the cell surface can be utilized as much as possible, thereby increasing the current density of the cell and ultimately improving the photoelectric conversion efficiency of the cell.

[0005] Currently, n-type TBC cells typically use silver paste and screen printing to prepare the metal electrodes for the p-type and n-type regions. Since both the p-type and n-type regions are silver electrodes, the battery cost increases significantly. Therefore, to address the high cost of silver electrodes in n-TBC cells, some companies or research institutions are using electroplating to prepare the metal electrodes. This involves sequentially electroplating nickel, copper, and tin metal electrodes on the back of the cell, thus achieving a silver-free metal electrode and reducing the production cost of the TBC cell. However, this method also brings a new problem. In addition to the high cost of electroplating equipment and investment, the wastewater treatment costs of electroplating technology will greatly increase the production cost of the battery. This is an environmentally unfriendly metal electrode preparation method and cannot be mass-produced in the short term.

[0006] Therefore, how to provide a TBC solar cell that is suitable for mass production and low in cost is an urgent problem to be solved by those skilled in the art.

[0007] Summary of the Invention

[0008] The purpose of the present invention is to provide a P-type TBC solar cell and a manufacturing method thereof, so as to solve the problems in the prior art of high production cost and inability to mass produce TBC cells.

[0009] To solve the above technical problems, the present invention provides a P-type TBC solar cell, comprising a P-type base silicon, wherein the backlight surface of the P-type base silicon comprises a patterned N-type region;

[0010] In the N-type region, the first tunneling layer, the N-type polysilicon layer, the first conductive shielding layer, the first passivation anti-reflection layer and the non-silver N fine gate are sequentially included from the backlight surface of the P-type base silicon outward;

[0011] The non-silver N fine grid penetrates the first passivation anti-reflection layer and contacts the first conductive shielding layer.

[0012] Optionally, in the P-type TBC solar cell, the backlight surface of the P-type silicon substrate further includes a patterned P-type region; the P-type region does not overlap with the N-type region;

[0013] In the P-type region, the second tunneling layer, the P-type polysilicon layer, the second conductive shielding layer, the second passivation anti-reflection layer and the non-silver P fine gate are sequentially included from the backlight surface of the P-type base silicon.

[0014] Optionally, in the P-type TBC solar cell, the first tunneling layer and the second tunneling layer are continuous and integrated tunneling layers;

[0015] and / or

[0016] The first passivation anti-reflection layer and the second passivation anti-reflection layer are continuous and integrated passivation anti-reflection layers.

[0017] Optionally, in the P-type TBC solar cell, the P-type region and the N-type region are strip regions alternately arranged on the backlight surface of the P-type silicon substrate.

[0018] Optionally, in the P-type TBC solar cell, the first conductive shielding layer and the second conductive shielding layer are made of the same material;

[0019] and / or

[0020] The first passivation anti-reflection layer and the second passivation anti-reflection layer are made of the same material.

[0021] Optionally, in the P-type TBC solar cell, the first passivation anti-reflection layer includes, from the inside to the outside, a first aluminum oxide passivation layer and a first silicon nitride anti-reflection layer.

[0022] Optionally, in the P-type TBC solar cell, the main grid of the P-type TBC solar cell is a silver main grid.

[0023] Optionally, in the P-type TBC solar cell, the P-type TBC solar cell is a busbar-less cell;

[0024] The N-type region and the P-type region of the P-type TBC solar cell are strip-shaped regions alternately arranged on the backlight surface of the P-type silicon substrate;

[0025] The P-type region includes a P fine gate and a P-region passivation anti-reflection layer;

[0026] The P fine gate penetrates the P region passivation anti-reflection layer and contacts the P-type base silicon;

[0027] The P fine grid is a continuous fine grid;

[0028] The N-type region is a segmented strip region composed of a plurality of N-type segments; there are interruptions between adjacent N-type segments;

[0029] The bottom surface of the interruption gap is consistent with the surface of the P-type region;

[0030] The middle interval is the placement area of ​​the welding strip corresponding to the P fine grid;

[0031] The N-type section is a placement area for the soldering strip corresponding to the non-silver N grid line.

[0032] A method for manufacturing a P-type TBC solar cell, wherein the backlight surface of a P-type silicon substrate includes a patterned N-type region and a patterned P-type region, comprising:

[0033] Disposing a first tunneling layer in the N-type region;

[0034] Disposing an N-type polysilicon layer on the surface of the first tunneling layer;

[0035] Disposing a first conductive shielding layer on the surface of the N-type polysilicon layer;

[0036] Disposing a first passivation anti-reflection layer on the surface of the first conductive shielding layer to obtain a cell precursor;

[0037] Metallizing the N-type region of the cell precursor to obtain a non-silver N-type fine grid penetrating the first passivation anti-reflection layer and contacting the first conductive shielding layer;

[0038] The P-type region of the cell precursor is metallized to obtain a P fine grid.

[0039] Optionally, in the method for manufacturing the P-type TBC solar cell, the process of obtaining the cell precursor includes:

[0040] A tunneling layer is provided on the entire backlight surface of the P-type silicon substrate;

[0041] An N-type polysilicon layer is provided on the tunneling layer in the N-type region; and a P-type polysilicon layer is provided on the tunneling layer in the P-type region to obtain a PN junction silicon wafer;

[0042] Providing a conductive shielding layer on the entire backlight surface of the PN junction silicon wafer;

[0043] The conductive shielding layer is etched by ultraviolet laser to separate the conductive shielding layer into a first conductive shielding layer on the surface of the N-type polysilicon and a second conductive shielding layer on the surface of the P-type polysilicon, thereby obtaining the cell precursor.

[0044] The present invention provides a P-type TBC solar cell comprising a P-type silicon substrate, the backlight surface of which includes a patterned N-type region. Within the N-type region, a first tunneling layer, an N-type polysilicon layer, a first conductive shielding layer, a first passivation anti-reflection layer, and a non-silver N-type fine grid are sequentially arranged from the backlight surface of the P-type silicon substrate outward. The non-silver N-type fine grid penetrates the first passivation anti-reflection layer and contacts the first conductive shielding layer. The present invention uses the non-silver N-type fine grid as a metal electrode in the N-type region on the backside of the cell, significantly reducing the production cost of the P-type TBC solar cell. Furthermore, a conductive shielding layer is provided between the non-silver N-type fine grid and the corresponding polysilicon to prevent the non-silver N-type fine grid from directly contacting the polysilicon with the metal paste during sintering, thereby damaging the polysilicon. Instead, the non-silver N-type fine grid achieves good ohmic contact with the conductive shielding layer, significantly reducing contact resistance and significantly increasing the cell's fill factor. Furthermore, the conductive shielding layer effectively reduces the cell's reverse saturation current density, increasing the cell's open-circuit voltage and improving the cell's photoelectric conversion efficiency. The present invention also provides a method for manufacturing a P-type TBC solar cell having the above beneficial effects. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] In order to more clearly illustrate the embodiments of the present invention or the technical solutions of the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0046] FIG1 is a schematic structural diagram of a specific embodiment of a P-type TBC solar cell provided by the present invention;

[0047] FIG2 is a schematic diagram showing the positional relationship between the fine grid and the welding ribbon of a specific embodiment of a P-type TBC solar cell provided by the present invention;

[0048] FIG3 is a schematic structural diagram of another specific embodiment of a P-type TBC solar cell provided by the present invention;

[0049] FIG4 is a schematic structural diagram of another specific embodiment of a P-type TBC solar cell provided by the present invention;

[0050] FIG5 is a schematic diagram of the three-dimensional structure of a specific embodiment of a P-type TBC solar cell provided by the present invention;

[0051] FIG6 is a schematic structural diagram of a specific embodiment of a P-type TBC solar cell provided by the present invention.

[0052] In the figure, it includes: 10-P-type base silicon, 21-first tunneling layer, 22-second tunneling layer, 31-N-type polysilicon layer, 32-P-type polysilicon layer, 41-first conductive blocking layer, 42-second conductive blocking layer, 51A-first aluminum oxide passivation layer, 51B-first silicon nitride anti-reflection layer, 52A-P region passivation layer, 52B-P region anti-reflection layer, 52A'-second aluminum oxide passivation layer, 52B'-second silicon nitride anti-reflection layer, 61-non-silver N fine gate, 62-P fine gate, 62'-non-silver P fine gate, 20-tunneling layer, 50-passivation anti-reflection layer, 71-front surface anti-reflection layer, 72-front surface passivation layer. DETAILED DESCRIPTION

[0053] In order to enable those skilled in the art to better understand the present invention, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0054] The core of the present invention is to provide a P-type TBC solar cell, a structural diagram of a specific embodiment of which is shown in FIG1 , referred to as specific embodiment 1, comprising a P-type silicon substrate 10, the backlight surface of the P-type silicon substrate 10 including a patterned N-type region;

[0055] In the N-type region, from the backlight side of the P-type silicon substrate 10 outward, the first tunneling layer 21, the N-type polysilicon layer 31, the first conductive shielding layer 41, the first passivation anti-reflection layer and the non-silver N fine gate 61 are sequentially included;

[0056] The non-silver N fine gate 61 penetrates the first passivation anti-reflection layer and contacts the first conductive shielding layer 41 .

[0057] Please refer to Figure 1 , which shows polysilicon disposed only within the N-type region. In other words, the P-type TBC solar cell only comprises the N-type polysilicon layer 31. Accordingly, the fine gate connected to the P-type region is referred to as a P fine gate 62. In the specific embodiment shown in Figure 1 , the P fine gate 62 directly contacts the P-type base silicon 10.

[0058] On the basis of the solar cell shown in FIG1 , the P-type TBC solar cell can be further defined as a busbar-less cell;

[0059] The N-type region and the P-type region of the P-type TBC solar cell are strip-shaped regions alternately arranged on the backlight surface of the P-type silicon substrate 10;

[0060] The P-type region includes a P fine gate 62 and a P-region passivation anti-reflection layer;

[0061] The P fine gate 62 penetrates the P region passivation anti-reflection layer and contacts the P-type base silicon 10;

[0062] The P fine gate 62 is a continuous fine gate;

[0063] The N-type region is a segmented strip region composed of a plurality of N-type segments; there are interruptions between adjacent N-type segments;

[0064] The bottom surface of the interruption gap is consistent with the surface of the P-type region;

[0065] The middle interval is the placement area of ​​the solder strip corresponding to the P fine grid 62;

[0066] The N-type section is a placement area for the soldering strip corresponding to the non-silver N grid line.

[0067] In the foregoing, a structure of a busbar-less P-type TBC solar cell is described, with the fine grid distribution on its backlight surface shown in FIG2 . As can be seen from FIG1 , the backlight surface of the cell shown in FIG2 is not a flat surface. Instead, the N-type region where the non-silver N-grid lines are provided is higher, while the P-type region where the P fine grids 62 are provided is lower. In the absence of a busbar, this would cause the soldering ribbons of the photovoltaic module to be obstructed by the higher N-type region, preventing close contact with the lower P fine grids 62. In this preferred embodiment, both the N-type and P-type regions are first configured as strips, and then the higher N-type region is segmented by interruptions. When soldering ribbons (indicated by A in FIG2 ) connecting different P fine grids 62 in series are provided, they are passed through the interruptions. This avoids interference with the soldering ribbons by the higher N-type region and ensures close contact between the soldering ribbons and the P fine grids 62. The soldering ribbons (indicated by B in FIG2 ) connecting different non-silver N-grid lines in series are provided through the N-type segments at the same position in different N-type regions.

[0068] The P-region passivation anti-reflection layer can refer to the first passivation anti-reflection layer, and is divided into a P-region passivation layer 52A and a P-region anti-reflection layer 52B from the inside to the outside. The material and thickness can also refer to the first passivation anti-reflection layer, which will not be repeated here.

[0069] As another specific embodiment, the P-type TBC solar cell can also be a solar cell with a busbar, wherein the busbar of the P-type TBC solar cell is a silver busbar. In this specific embodiment, the busbar, which only occupies a small proportion of the back electrode of the cell, is set as a silver busbar to achieve the purpose of improving the busbar current collection effect and facilitating component welding. Of course, the P-type TBC solar cell can also be a busbar-free cell, and the choice can be made according to actual circumstances.

[0070] The solid content of the silver paste corresponding to the silver busbars ranges from 50% to 90%, including any of 50.0%, 64.2%, or 90.0%. Furthermore, the thickness of the first conductive shielding layer 41 ranges from 30 nanometers to 150 nanometers, including any of 30.0 nanometers, 48.5 nanometers, or 150.0 nanometers. Furthermore, the number of silver busbars ranges from 5 to 20, including any of 5.0, 12.0, or 20.0.

[0071] In addition, the main grid of the P-type TBC solar cell of the cell sheet in the present invention can be an aluminum main grid, a silver main grid, or a main grid made of other materials, which is not limited in the present invention.

[0072] Preferably, the first passivation and anti-reflection layer includes, from the inside out, a first aluminum oxide passivation layer 51A and a first silicon nitride anti-reflection layer 51B. Referring to FIG1 , in this embodiment, the passivation and anti-reflection functions are implemented by two different layers, respectively, to achieve better passivation and anti-reflection effects. Furthermore, using aluminum oxide as the passivation layer and silicon nitride as the anti-reflection layer is a cost-effective and efficient option. Of course, other materials can also be selected for the passivation and anti-reflection layers according to actual circumstances, and the present invention is not limited thereto.

[0073] The conductive barrier layer in this invention generally refers to conductive oxides, nitrides, and fluorides, such as In2O3, SnO2, ZnO, CdO, TiN, In2O3:Sn (ITO), ZnO:In (IZO), ZnO:Al (AZO), SnO2:F (FTO), TiO2:Ta; or mixed oxides such as In2O3-ZnO, CdIn2O4, Cd2SnO4, and Zn2SnO4. AZO is a commonly used material, and will be used as an example below. The work function of AZO is more closely matched to the non-silver N fine grid 61, resulting in lower transmission losses within the cell and significantly improving the cell's photoelectric conversion efficiency.

[0074] The non-silver N fine grid 61 can be one of aluminum fine grid (Al), copper fine grid (Cu), nickel fine grid (Ni), titanium tungsten fine grid (TiW), or a plurality of alloy material fine grids.

[0075] Before preparing the metal electrode (i.e., the non-silver N fine gate 61), the present invention deposits a layer of AZO (zinc oxide ZnO doped Al2O3) on the back side of the N-type polysilicon layer 31. The sum of the costs of the first conductive shielding layer 41 and the non-silver N fine gate 61 is still much lower than the cost of directly using metallic silver to prepare the metal electrode.

[0076] It should be noted that aluminum is extremely active and can easily burn through polysilicon at high temperatures. As a result, metallic aluminum cannot currently be used directly as a gate line on the surface of the N-type polysilicon layer 31. Therefore, the first conductive shielding layer 41 is required for isolation to prevent the aluminum paste used to prepare the non-silver N fine gate 61 from directly contacting the polysilicon. During the metallization process, the aluminum paste sintered at high temperature can form a good ohmic contact between the non-silver N fine gate 61 and the surface of the first conductive shielding layer 41, with a contact resistivity of <1.5mΩcm. 2 .

[0077] The P-type TBC solar cell provided by the present invention includes a P-type base silicon 10, the backlight surface of the P-type base silicon 10 includes a patterned N-type region; within the N-type region, from the backlight surface of the P-type base silicon 10 outward, it includes a first tunneling layer 21, an N-type polysilicon layer 31, a first conductive shielding layer 41, a first passivation anti-reflection layer and a non-silver N fine grid 61; the non-silver N fine grid 61 penetrates the first passivation anti-reflection layer and contacts the first conductive shielding layer 41. The present invention uses a non-silver N fine grid 61 as a metal electrode in the N-type region on the back of the cell, which can greatly reduce the production cost of the P-type TBC solar cell. At the same time, a conductive shielding layer is provided between the non-silver N fine grid 61 and the corresponding polysilicon to prevent the non-silver N fine grid 61 from directly contacting the polysilicon with the metal slurry during the sintering process, thereby damaging the polysilicon. Instead, the non-silver N fine grid 61 achieves good ohmic contact with the conductive shielding layer, which greatly reduces the contact resistance and significantly increases the fill factor of the cell. At the same time, the conductive shielding layer can also effectively reduce the reverse saturation current density of the cell, increase the open circuit voltage of the cell, and improve the photoelectric conversion efficiency of the cell.

[0078] On the basis of the first embodiment, the backlight surface structure of the P-type TBC solar cell is further improved to obtain the second embodiment, the corresponding structural diagram of which is shown in FIG3 , including a P-type silicon substrate 10, the backlight surface of which includes a patterned N-type region;

[0079] In the N-type region, from the backlight side of the P-type silicon substrate 10 outward, the first tunneling layer 21, the N-type polysilicon layer 31, the first conductive shielding layer 41, the first passivation anti-reflection layer and the non-silver N fine gate 61 are sequentially included;

[0080] The non-silver N fine grid 61 penetrates the first passivation anti-reflection layer and contacts the first conductive shielding layer 41;

[0081] The backlight surface of the P-type silicon substrate 10 further includes a patterned P-type region; the P-type region does not overlap with the N-type region;

[0082] In the P-type region, from the backlight side of the P-type silicon substrate 10 outward, the second tunneling layer 22, the P-type polysilicon layer 32, the second conductive shielding layer 42, the second passivation anti-reflection layer and the non-silver P fine gate 62' are sequentially included.

[0083] In this specific embodiment, the P-type polysilicon layer 32 is added to the P-type TBC solar cell as a P+ region to further improve the photoelectric conversion efficiency of the solar cell. At the same time, the fine grid structure corresponding to the P-type polysilicon layer 32 is also replaced by a combined structure of a conductive shielding layer and a non-silver fine grid, that is, the second conductive shielding layer 42 and the non-silver P fine grid 62'.

[0084] As a specific embodiment, the first tunneling layer 21 and the second tunneling layer 22 are continuous and integrated tunneling layers;

[0085] and / or

[0086] The first passivation anti-reflection layer and the second passivation anti-reflection layer are continuous and integrated passivation anti-reflection layers.

[0087] Please refer to Figure 4. In other words, in this specific embodiment, the tunneling layer located in the P-type region and the N-type region can be an integral layer (indicated by 20 in Figure 4), which can be manufactured at one time during production. Similarly, the first passivation anti-reflection layer and the second passivation anti-reflection layer can also be an integral layer (indicated by 50 in Figure 4). The passivation anti-reflection layers of the two regions can be prepared at one time during production, and there is no need to distinguish between the two structures located in different regions, which simplifies the production process and improves production efficiency.

[0088] As a specific embodiment, the first conductive shielding layer 41 and the second conductive shielding layer 42 are made of the same material;

[0089] and / or

[0090] The first passivation anti-reflection layer and the second passivation anti-reflection layer are made of the same material.

[0091] In this specific embodiment, all the conductive shielding layers in the P-type TBC solar cell are made of the same material, and all the passivation anti-reflection layers are made of the same material, which further simplifies the production process and improves production efficiency.

[0092] The structure of the second passivation anti-reflection layer may refer to the structure of the first passivation anti-reflection layer, and includes a second aluminum oxide passivation layer 52A′ and a second silicon nitride anti-reflection layer 52B′ from the inside to the outside.

[0093] Because the first conductive shielding layer 41 is provided between the non-silver N fine gate 61 and the N-type polysilicon layer 31, and the second conductive shielding layer 42 is provided between the non-silver P fine gate 62' and the P-type polysilicon layer 32, the reverse saturation current density (J0, metal) caused by the metal on the surface of the P-type polysilicon layer 32 and the surface of the N-type polysilicon layer 31 is 0, and the reverse saturation current density (J01) of the quasi-neutral region and the reverse saturation current density (J02) of the space charge region of the battery can be effectively reduced, thereby improving the open circuit voltage of the battery. Finally, the contact resistivity of the P-type polysilicon region is 0.5 mΩ·cm 2 -1.5mΩ·cm 2 The contact resistivity of the N-type polysilicon layer 31 is 0.5 mΩ·cm 2 -1.5mΩ·cm 2 ; J01 is 10fA / cm 2 -20fA / cm 2 ; J02 is 0.5nA / cm 2 -3nA / cm 2 ,In addition, the thermal stability temperature of the two conductive barrier layers is above 500 ,℃, and can generally reach 900 ,℃, and the resistivity decreases with the increase of ,the Al2O3 doping ratio in AZO.

[0094] Of course, according to common sense in related technologies, the N-type polysilicon layer 31 and the P-type polysilicon layer 32 should be insulated. As a specific implementation, the N-type polysilicon layer 31 and the P-type polysilicon layer 32 may not be in contact with each other, and the first conductive shielding layer 41 and the second conductive shielding layer 42 should also be insulated, such as the two conductive shielding layers are not in contact with each other.

[0095] Of course, FIG5 is only a specific embodiment of the P-type TBC solar cell. The N-type region and the P-type region in FIG5 are staggered with each other. In actual production, the N-type region and the P-type region on the backlight surface of the P-type TBC solar cell can also be divided in other forms.

[0096] In a specific embodiment, the P-type and N-type regions are strip-shaped regions alternately disposed on the backlight surface of the P-type silicon substrate 10. This structure significantly reduces the difficulty of fabricating the corresponding conductive shielding layer and facilitates the subsequent laying of the corresponding non-silver fine grid on the corresponding conductive shielding layer to form interdigitated electrodes, thereby improving the production efficiency and product yield of the cell. A specific embodiment of the interdigitated electrodes on the backlight surface of the P-type TBC solar cell can be seen in Figure 5, which is a schematic diagram of a three-dimensional structure of the P-type TBC solar cell provided by the present invention.

[0097] On the other hand, the proportion of aluminum oxide in the conductive shielding layer (including at least one of the first conductive shielding layer 41 and the second conductive shielding layer 42) in the present application is in the range of 2% to 25%, including endpoint values, such as any one of 2.0%, 16.2% or 25.0%, and the rest is zinc oxide.

[0098] On the other hand, the number of fine gates corresponding to the N-type region and / or the P-type region ranges from 120 to 200, including endpoint values, such as any one of 120.0, 164.0 or 200.0; the width of the non-silver N fine gate 61 and / or the non-silver P fine gate 62' ranges from 100 microns to 200 microns, including endpoint values, such as any one of 100.0 microns, 154.2 microns or 200.0 microns; the height of the non-silver N fine gate 61 and / or the non-silver P fine gate 62' ranges from 10 microns to 40 microns, including endpoint values, such as any one of 10.0 microns, 14.2 microns or 40.0 microns.

[0099] Of course, in addition to the structural description of the backlight surface of the P-type TBC solar cell in the previous article, the P-type TBC solar cell also includes other structures. Please refer to the P-type TBC solar cell in Figure 1. In the specific embodiment represented by Figure 1, the light-facing surface of the cell is a velvet surface, and from the inside to the outside includes a front surface passivation layer 72 and a front surface anti-reflection layer 71.

[0100] The thickness of the tunneling layer (including at least one of the first tunneling layer 21 and the second tunneling layer 22) in the present invention is in the range of 1 nm to 8 nm, including any one of endpoint values, such as 1.0 nm, 4.1 nm or 8.0 nm; the thickness of the N-type polysilicon layer 31 and / or the P-type polysilicon layer 32 is in the range of 80 nm to 200 nm, including any one of endpoint values, such as 80.0 nm, 162.0 nm or 200.0 nm; the doping concentration of the N-type polysilicon layer 31 is in the range of 1E20 atoms / cm 3 to 6E20atoms / cm 3 , including endpoint values; the doping concentration of the P-type polysilicon layer 32 is in the range of 1E18atoms / cm3 to 1E20 atoms / cm 3 Preferably, the thickness of the N-type polysilicon layer 31 may be the same as the thickness of the P-type polysilicon layer 32 to reduce production difficulty.

[0101] The above parameter ranges are preferred values ​​obtained after a large number of theoretical calculations and actual tests. Of course, other values ​​can also be selected according to actual conditions, and the present invention is not limited thereto.

[0102] The present invention also provides a method for manufacturing a P-type TBC solar cell. A flow chart of a specific embodiment thereof is shown in FIG6 , which is referred to as specific practical method three. The backlight surface of the P-type substrate silicon includes a patterned N-type region and a patterned P-type region, including:

[0103] S101: Disposing a first tunneling layer in the N-type region.

[0104] S102: Disposing an N-type polysilicon layer on the surface of the first tunneling layer.

[0105] S103: Disposing a first conductive shielding layer on the surface of the N-type polysilicon layer.

[0106] S104: Disposing a first passivation anti-reflection layer on the surface of the first conductive shielding layer to obtain a cell precursor.

[0107] S105: Metallizing the N-type region of the cell precursor to obtain a non-silver N-type fine grid penetrating the first passivation anti-reflection layer and contacting the first conductive shielding layer.

[0108] S106: Metallizing the P-type region of the cell precursor to obtain a P fine grid.

[0109] This specific embodiment corresponds to the P-type TBC solar cell in the foregoing text. Therefore, for the parameters of each structure in this specific embodiment, please refer to the description of the P-type TBC solar cell in the foregoing text, and no further details will be given here.

[0110] There is no fixed order for step S105 and step S106, and the order can be changed according to actual conditions.

[0111] Of course, in addition to the above steps, a front surface passivation layer and a front surface anti-reflection layer may be sequentially provided on the front surface of the P-type silicon substrate.

[0112] As a preferred embodiment, the process of obtaining the cell precursor includes:

[0113] A1: A tunneling layer is provided on the entire backlight surface of the P-type silicon substrate.

[0114] A2: An N-type polysilicon layer is provided on the tunneling layer in the N-type region; and a P-type polysilicon layer is provided on the tunneling layer in the P-type region to obtain a PN junction silicon wafer.

[0115] Of course, in order for the P-type TBC solar cell to work properly, the N-type polysilicon layer and the P-type polysilicon layer in the PN junction silicon wafer should also be isolated. As a preferred embodiment, the configuration of the N-type polysilicon layer and the P-type polysilicon layer includes:

[0116] B1: a polysilicon layer is provided on the surface of the tunneling layer.

[0117] B2: performing phosphorus doping and boron doping on the polysilicon layer according to the region division of the N-type region and the P-type region to obtain an N-type polysilicon layer and a P-type polysilicon layer.

[0118] B3: Separating the N-type polysilicon layer and the P-type polysilicon layer by using ultraviolet laser.

[0119] After separation, the minority carrier lifetime decay value in the battery is less than about 10us, and the relative decay of the minority carrier lifetime is less than 0.9%, further extending the minority carrier lifetime and improving the battery's photoelectric conversion efficiency. Furthermore, the ultraviolet laser is a picosecond laser, which improves the separation effect.

[0120] The tunneling layer and the polysilicon layer in this specific embodiment can be deposited by PECVD or LPCVD (low pressure chemical vapor deposition).

[0121] A3: A conductive shielding layer is provided on the entire backlight surface of the PN junction silicon wafer.

[0122] The process of setting the conductive shielding layer in this step includes:

[0123] A conductive shielding layer is provided on the entire backlight surface of the PN junction silicon wafer by magnetron sputtering or reactive plasma deposition.

[0124] The above two methods are mature in technology, low in cost and suitable for large-scale production.

[0125] A4: Etching the conductive shielding layer by ultraviolet laser to separate the conductive shielding layer into a first conductive shielding layer on the surface of the N-type polysilicon and a second conductive shielding layer on the surface of the P-type polysilicon to obtain the cell precursor.

[0126] In this step, the portion of the conductive shielding layer corresponding to the N-type region and the portion corresponding to the P-type region are divided to obtain the first conductive shielding layer and the second conductive shielding layer.

[0127] In this specific embodiment, the setting process of the first conductive shielding layer and the second conductive shielding layer is further disassembled. The conductive shielding layer is first set on the entire surface, and then the AZO on the N-type area and the P-type area are separated by laser etching to obtain the first conductive shielding layer and the second conductive shielding layer. This simplifies the step process and takes into account high production efficiency and low production cost.

[0128] Furthermore, the energy range of the ultraviolet laser is 0.01W-5W, the laser frequency is 100Khz-500Khz, the spot diameter is 10um-30um, the minority carrier lifetime attenuation value is 0us-10us, and the relative attenuation is 0%-0.9%, further improving the minority carrier lifetime and improving the battery photoelectric conversion efficiency.

[0129] The present invention provides a method for manufacturing a P-type TBC solar cell, in which the backlight surface of the P-type base silicon includes a patterned N-type region and a patterned P-type region, and comprises providing a first tunneling layer in the N-type region; providing an N-type polysilicon layer on the surface of the first tunneling layer; providing a first conductive shielding layer on the surface of the N-type polysilicon layer; providing a first passivation anti-reflection layer on the surface of the first conductive shielding layer to obtain a cell precursor; metallizing the N-type region of the cell precursor to obtain a non-silver N fine grid that penetrates the first passivation anti-reflection layer and contacts the first conductive shielding layer; and metallizing the P-type region of the cell precursor to obtain a P fine grid. The present invention uses a non-silver N fine grid as a metal electrode in the N-type region on the back of the battery, which can greatly reduce the production cost of the P-type TBC solar cell. At the same time, a conductive shielding layer is provided between the non-silver N fine grid and the corresponding polycrystalline silicon to prevent the non-silver N fine grid from directly contacting the polycrystalline silicon with the metal slurry during the sintering process, thereby damaging the polycrystalline silicon. Instead, the non-silver N fine grid achieves good ohmic contact with the conductive shielding layer, which greatly reduces the contact resistance and significantly increases the fill factor of the battery. At the same time, the conductive shielding layer can also effectively reduce the reverse saturation current density of the battery, increase the open circuit voltage of the battery, and improve the photoelectric conversion efficiency of the battery.

[0130] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from the other embodiments. Reference can be made to the descriptions of the identical or similar parts between the various embodiments. For the devices disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the descriptions are relatively simple, and the relevant parts can be referred to the descriptions of the methods.

[0131] It should be noted that, in this specification, relational terms such as first and second, etc. are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "comprises", "comprising" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "comprising a ..." does not exclude the presence of other identical elements in the process, method, article or device comprising the element.

[0132] The above describes in detail the P-type TBC solar cell and its manufacturing method provided by the present invention. Specific examples are used herein to illustrate the principles and implementation methods of the present invention. The above examples are intended only to facilitate understanding of the present invention's methods and core concepts. It should be noted that those skilled in the art will be able to make various improvements and modifications to the present invention without departing from the principles of the present invention, and such improvements and modifications fall within the scope of protection of the claims.

Claims

1. A P-type TBC solar cell, characterized in that, It includes a P-type substrate silicon, and the backlight surface of the P-type substrate silicon includes a patterned N-type region; Within the N-type region, from the backlight surface of the P-type substrate silicon outward, it successively includes a first tunneling layer, an N-type polysilicon layer, a first conductive shielding layer, a first passivation and antireflection layer, and a non-silver N fine grid; The non-silver N fine grid penetrates through the first passivation and antireflection layer and contacts the first conductive shielding layer.

2. The P-type TBC solar cell according to claim 1, wherein The backlight surface of the P-type substrate silicon further includes a patterned P-type region; the P-type region does not overlap with the N-type region; Within the P-type region, from the backlight surface of the P-type substrate silicon outward, it successively includes a second tunneling layer, a P-type polysilicon layer, a second conductive shielding layer, a second passivation and antireflection layer, and a non-silver P fine grid.

3. The P-type TBC solar cell according to claim 2, wherein The first tunneling layer and the second tunneling layer are a continuous and integral tunneling layer; and / or The first passivation and antireflection layer and the second passivation and antireflection layer are a continuous and integral passivation and antireflection layer.

4. The P-type TBC solar cell according to claim 2, characterized in that, The P-type region and the N-type region are strip-shaped regions alternately arranged on the backlight surface of the P-type substrate silicon.

5. The P-type TBC solar cell according to claim 2, wherein The first conductive shielding layer and the second conductive shielding layer are made of the same material; and / or The first passivation and antireflection layer and the second passivation and antireflection layer are made of the same material.

6. The P-type TBC solar cell according to claim 1, characterized in that, The first passivation and antireflection layer successively includes a first aluminum oxide passivation layer and a first silicon nitride antireflection layer from the inside to the outside.

7. The P-type TBC solar cell according to claim 1, wherein The main grid of the P-type TBC solar cell is a silver main grid.

8. The P-type TBC solar cell according to claim 1, characterized in that, The P-type TBC solar cell is a main-gridless cell; The N-type region and the P-type region of the P-type TBC solar cell are strip-shaped regions alternately arranged on the backlight surface of the P-type substrate silicon; The P-type region includes a P fine grid and a P-region passivation and antireflection layer; The P fine grid penetrates through the P-region passivation and antireflection layer and contacts the P-type substrate silicon; The P fine grid is a continuous fine grid; The N-type region is a segmented strip-shaped region composed of multiple N-type segments; there is an interruption interval between adjacent N-type segments; The bottom surface of the interruption interval is consistent with the surface of the P-type region; The middle section interval is the placement area for the solder tape corresponding to the P fine grid; The N-type segment is the placement area for the solder tape corresponding to the non-silver N grid line.

9. A manufacturing method of a P-type TBC solar cell, characterized in that, The backlight surface of the P-type substrate silicon includes a patterned N-type region and a patterned P-type region, including: A first tunneling layer is provided in the N-type region; An N-type polysilicon layer is provided on the surface of the first tunneling layer; A first conductive shielding layer is provided on the surface of the N-type polysilicon layer; A first passivation and antireflection layer is provided on the surface of the first conductive shielding layer to obtain a cell precursor; The N-type region of the cell precursor is metallized to obtain a non-silver N fine grid that penetrates through the first passivation and antireflection layer and contacts the first conductive shielding layer; The P-type region of the cell precursor is metallized to obtain a P fine grid.

10. The manufacturing method of the P-type TBC solar cell according to claim 9, characterized in that, The process for obtaining the cell precursor includes: A tunneling layer is provided on the entire backlight surface of the P-type substrate silicon; An N-type polysilicon layer is provided on the tunneling layer within the N-type region; a P-type polysilicon layer is provided on the tunneling layer within the P-type region to obtain a P-N junction silicon wafer; A conductive shielding layer is provided on the entire backlight surface of the P-N junction silicon wafer; Etch the conductive shielding layer by ultraviolet laser to divide the conductive shielding layer into a first conductive shielding layer on the surface of the N-type polysilicon and a second conductive shielding layer on the surface of the P-type polysilicon, thereby obtaining the cell precursor.

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