A bc battery, a preparation method thereof and a photovoltaic module

Abstract

The application provides a BC battery, a preparation method thereof and a photovoltaic module. The material of the conductive electrode of the BC battery comprises a base metal; the BC battery comprises an N-type crystalline silicon substrate, the N-type crystalline silicon substrate comprises opposite front and back surfaces, the back surface of the N-type crystalline silicon substrate comprises an N region and a P region which are arranged in a cross shape and do not contact each other; the N region is provided with an N conductive layer, the P region is provided with a P conductive layer, and the carrier concentration of the N conductive layer is lower than that of the P conductive layer. By arranging the P conductive layer with higher carrier concentration in the P region and the N conductive layer with lower carrier concentration in the N region, the ohmic contact between the n-type polycrystalline silicon and the p-type amorphous silicon and the metal paste is effectively reduced, the current density is improved, and the photoelectric efficiency of the solar cell is improved.

Description

Technical Field

[0001] This invention relates to the field of photovoltaic technology, specifically to BC cells, and more particularly to a BC cell, its preparation method, and a photovoltaic module. Background Technology

[0002] Transparent conductive oxide (TCO) films possess excellent optoelectronic properties such as wide bandgap, high transmittance in the visible spectrum, and low resistivity, thus showing broad application prospects in the field of optoelectronic devices. Due to their low contact resistance with crystalline silicon, TCO films are widely used on the back side of photovoltaic cells to reduce series resistance and improve short-circuit current. However, TCO films have many lattice defects at grain boundaries. When applied to base metal conductive electrodes (BC) cells, these defects create diffusion channels for metal ions into the cell interior, leading to a high probability of carrier recombination and poor passivation contact. Currently, existing technologies typically optimize the composition of copper paste or fabricate multilayer transparent conductive oxide films to reduce the contact resistance between crystalline silicon and the metal paste, thereby improving cell efficiency.

[0003] CN119133304A discloses a method for preparing a heterojunction solar cell composite TCO, comprising depositing a first transparent conductive layer, a second transparent conductive layer and a metal conductive layer on a P-type doped amorphous silicon layer; depositing a third transparent conductive layer, a fourth transparent conductive layer and a fifth transparent conductive layer on an N-type doped amorphous silicon layer; printing back grid lines on the metal conductive layer and printing front grid lines on the fifth transparent conductive layer; the invention uses the above-mentioned stacked layers to have photoelectric properties similar to ITO, and the metal thin film has good conductivity, which can replace part of the silver paste to transport electrons, thereby reducing the amount of indium used and reducing silver consumption.

[0004] CN106024919A discloses an amorphous silicon thin-film solar cell and its manufacturing method. The amorphous silicon thin-film solar cell comprises a flexible PET substrate layer, a SiO2 light-trapping layer, a first electrode TCO layer, a p-type amorphous silicon layer, a p-type buffer layer, an i-type amorphous silicon layer, an n-type amorphous silicon layer, a second electrode TCO layer, and a back reflective layer, sequentially connected. By depositing the first electrode TCO layer and the second electrode TCO layer on the SiO2 light-trapping layer and the n-type amorphous silicon layer, respectively, contamination of the intrinsic i-type and n-type amorphous silicon layers is effectively prevented.

[0005] CN119943469A discloses a copper paste, a method for preparing the copper paste, and an N-type crystalline silicon solar cell. The copper paste comprises organic additives, micron-sized spherical copper powder, nano-sized spherical copper powder, an organic binder, and glass powder. The organic additives constitute 1.5% to 2.2% of the copper paste by mass; the micron-sized spherical copper powder constitutes 70% to 77% of the copper paste by mass; the nano-sized spherical copper powder constitutes 3% to 5% of the copper paste by mass; the organic binder constitutes 15.3% to 21.3% of the copper paste by mass; and the glass powder constitutes 2.2% to 2.5% of the copper paste by mass. This invention optimizes the composition of the copper paste, enabling its application in solar cells.

[0006] Therefore, it is of great significance to provide a solar cell based on a base metal conductive electrode that can effectively prevent metal ions from diffusing into the silicon substrate, has good passivation contact performance. Summary of the Invention

[0007] To address the shortcomings of existing technologies, the present invention aims to provide a BC cell, its fabrication method, and a photovoltaic module. By setting a P-conductive layer with higher carrier concentration in the P-region and an N-conductive layer with lower carrier concentration in the N-region of the interdigitated BC cell, the present invention can effectively reduce the ohmic contact between n-type polycrystalline silicon and p-type amorphous silicon and the metal paste, thereby increasing the current density and ultimately improving the photoelectric efficiency of the solar cell.

[0008] To achieve this objective, the present invention adopts the following technical solution:

[0009] In a first aspect, the present invention provides a BC battery, wherein the conductive electrode of the BC battery is made of base metal; the BC battery includes an N-type crystalline silicon substrate, the N-type crystalline silicon substrate includes a front side and a back side opposite to each other, the back side of the N-type crystalline silicon substrate includes N-regions and P-regions arranged in a cross pattern but not in contact; an N-conductive layer is disposed in the N-region, and a P-conductive layer is disposed in the P-region, wherein the carrier concentration of the N-conductive layer is lower than the carrier concentration of the P-conductive layer.

[0010] This invention utilizes the difference in resistivity between n-type polycrystalline silicon in the N region and p-type amorphous silicon in the P region, resulting from the different doping processes of the two materials, in a BC cell with an interdigitated structure. A high-mobility, high-carrier-concentration P-conductive layer is formed in the P region (with higher resistivity), while a low-mobility, low-carrier-concentration N-conductive layer is formed in the N region (with lower resistivity). This creates an interdigitated conductive layer structure, effectively reducing the ohmic contact between the n-type polycrystalline silicon and p-type amorphous silicon and the metal paste, thereby increasing the current density and improving the photoelectric efficiency of the solar cell.

[0011] The "high / low mobility" and "high / low carrier concentration" mentioned in this invention refer only to the relative high and low mobility and carrier concentration of carriers in the P conductive layer and the N conductive layer in the same specific BC battery, and are not limitations on specific numerical values.

[0012] In this invention, the conductive electrode is made of base metal, specifically including any one or at least two alloys of copper, aluminum, or zinc, such as copper-aluminum alloy, copper-zinc alloy, or aluminum-zinc alloy.

[0013] Preferably, the carrier concentrations in the N-conductive layer and the P-conductive layer are each independently 1.0 × 10⁻⁶. 20 cm -3 ~3.0×10 20 cm -3 .

[0014] Preferably, the carrier mobility in the N-conductive layer and the P-conductive layer is independently 30 cm⁻¹. 2 ·V -1 ·s -1 ~130cm 2 ·V -1 ·s -1 .

[0015] Preferably, the materials of the P-conductive layer and the N-conductive layer each independently comprise indium tin oxide and / or tungsten-doped indium tin oxide.

[0016] Preferably, on the front side of the N-type crystalline silicon substrate, a hydrogenated amorphous silicon layer and a silicon nitride antireflection layer are sequentially disposed in a direction away from the back side.

[0017] Preferably, the N region is provided with a tunneling oxide layer, an n-type polycrystalline silicon doped layer, an aluminum oxide passivation layer, an N-conductive layer, and a metal electrode in sequence along the direction away from the front side of the N-type crystalline silicon substrate.

[0018] Preferably, the P region is provided with an intrinsic hydrogenated amorphous silicon layer, a p-type hydrogenated amorphous silicon layer, an aluminum oxide passivation layer, a P-conductive layer, and a metal electrode in sequence along the direction away from the front side of the N-type crystalline silicon substrate.

[0019] Preferably, an aluminum oxide passivation layer is provided on the exposed silicon substrate surface at the interval between the N region and the P region.

[0020] In a second aspect, the present invention provides a method for preparing a BC battery as described in the first aspect, the method comprising: depositing transparent conductive oxides in an N-region and a P-region respectively using argon and oxygen as reaction gases; annealing to prepare an N-conductive layer in the N-region and a P-conductive layer in the P-region; and subjecting the N-conductive layer and the P-conductive layer to ozone treatment respectively.

[0021] This invention induces the formation of a denser high-oxidation-state metal oxide layer on the surface of the annealed transparent conductive oxide layer by ozone treatment. The formed high-oxidation-state metal oxide layer can form chemical bonds with base metal ions (for example, when the base metal is Cu, a Cu-O bond is formed), anchoring the base metal ions on the conductive layer surface. This better prevents the base metal ions from diffusing into the silicon substrate, reduces carrier recombination, and improves passivation contact.

[0022] Preferably, the ozone treatment includes treating the N-conductive layer and the P-conductive layer with a 3wt% to 8wt% ozone solution.

[0023] Preferably, the ozone treatment time is 180s to 250s.

[0024] Preferably, the deposition pressure is 10. -4 Pa~10 -2 Pa.

[0025] Preferably, the deposition temperature is 20℃~200℃.

[0026] Preferably, during the deposition process, the partial pressure of water vapor is ≤1.0×10⁻⁶. -3 Pa.

[0027] Preferably, the annealing temperature is 160℃~200℃.

[0028] Preferably, the annealing time is 30 min to 100 min.

[0029] Preferably, the method of depositing the transparent conductive oxide includes any one of magnetron sputtering, evaporation, or ion plating.

[0030] Thirdly, the present invention provides a photovoltaic module comprising the BC cell as described in the first aspect.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] (1) In the BC cell with interdigitated structure, the present invention forms an interdigitated conductive layer structure by setting a P conductive layer with high mobility and high carrier concentration in the P region with higher resistivity and an N conductive layer with low mobility and low carrier concentration in the N region with lower resistivity, thereby effectively reducing the ohmic contact between n-type polycrystalline silicon and p-type amorphous silicon and metal paste, thereby increasing the current density and improving the photoelectric efficiency of the solar cell.

[0033] (2) By subjecting the annealed transparent conductive oxide layer to ozone treatment, the present invention induces the formation of a denser high-oxidation-state metal oxide layer on the surface of the transparent conductive oxide layer, thereby forming chemical bonds with base metal ions, anchoring the base metal ions on the surface of the conductive layer, better preventing the base metal ions from diffusing into the silicon substrate, reducing carrier recombination, and improving passivation contact performance. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of the BC battery in Embodiment 1 of the present invention.

[0035] Among them, 1-silicon nitride antireflection layer; 2-intrinsic hydrogenated amorphous silicon layer; 3-tunneling oxide layer; 4-n-type polycrystalline silicon doped layer; 5-alumina passivation layer; 6-P-conductive layer; 7-metal electrode; 8-p-type hydrogenated amorphous silicon layer; 9-N-conductive layer. Detailed Implementation

[0036] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention.

[0037] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit this application; the terms “comprising” and “having” and any variations thereof in this application are intended to cover non-exclusive inclusion.

[0038] In the description of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary or secondary relationship of the indicated technical features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly defined.

[0039] In one specific embodiment, the present invention provides a BC battery, wherein the conductive electrode of the BC battery is made of base metal; the BC battery includes an N-type crystalline silicon substrate, the N-type crystalline silicon substrate includes a front side and a back side opposite to each other, the back side of the N-type crystalline silicon substrate includes N-regions and P-regions arranged in a cross pattern but not in contact; an N-conductive layer is disposed in the N-region, and a P-conductive layer is disposed in the P-region, wherein the carrier concentration of the N-conductive layer is lower than the carrier concentration of the P-conductive layer.

[0040] This invention utilizes the difference in resistivity between n-type polycrystalline silicon in the N region and p-type amorphous silicon in the P region, resulting from the different doping processes of the two materials, in a BC cell with an interdigitated structure. A high-mobility, high-carrier-concentration P-conductive layer is formed in the P region (with higher resistivity), while a low-mobility, low-carrier-concentration N-conductive layer is formed in the N region (with lower resistivity). This creates an interdigitated conductive layer structure, effectively reducing the ohmic contact between the n-type polycrystalline silicon and p-type amorphous silicon and the metal paste, thereby increasing the current density and improving the photoelectric efficiency of the solar cell.

[0041] In some embodiments, the carrier concentrations in the N-conductive layer and the P-conductive layer are each independently 1.0 × 10⁻⁶. 20 cm -3 ~3.0×10 20 cm -3 For example, it could be 1.0 × 10 20 cm -3 1.2×10 20 cm -3 1.4×10 20 cm -3 1.6×10 20 cm -3 1.8×10 20 cm -3 2.0×10 20 cm -3 2.2×10 20 cm -3 2.4×10 20 cm -3 2.6×10 20 cm -3 2.8×10 20 cm -3 Or 3.0×10 20 cm -3 This includes, but is not limited to, the listed values; other unlisted values ​​within the range also apply.

[0042] In some embodiments, the carrier mobility in the N-conductive layer and the P-conductive layer is independently 30 cm⁻¹. 2 ·V -1 ·s -1 ~130cm 2 ·V -1 ·s -1 For example, it could be 30cm 2 ·V -1 ·s -1 40cm 2 ·V -1 ·s -150cm 2 ·V -1 ·s -1 60cm 2 ·V -1 ·s -1 70cm 2 ·V -1 ·s -1 80cm 2 ·V -1 ·s -1 90cm 2 ·V -1 ·s -1 100cm 2 ·V -1 ·s -1 110cm 2 ·V -1 ·s -1 120cm 2 ·V -1 ·s -1 Or 130cm 2 ·V -1 ·s -1 This includes, but is not limited to, the listed values; other unlisted values ​​within the range also apply.

[0043] In some embodiments, the materials of the P-conductive layer and the N-conductive layer each independently comprise indium tin oxide and / or tungsten-doped indium tin oxide.

[0044] In some embodiments, the thickness of the P conductive layer is ≤100nm, for example, it can be 10nm, 15nm, 20nm, 30nm, 40nm, 50nm, 60nm, 70nm, 80nm, 90nm or 100nm, including but not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0045] In some embodiments, a hydrogenated amorphous silicon layer and a silicon nitride antireflection layer are sequentially disposed on the front side of the N-type crystalline silicon substrate in a direction away from the back side.

[0046] In some embodiments, the N region is provided with a tunneling oxide layer, an n-type polycrystalline silicon doped layer, an aluminum oxide passivation layer, an N-conductive layer, and a metal electrode in sequence along the direction away from the front side of the N-type crystalline silicon substrate.

[0047] In some embodiments, the P region is provided with an intrinsic hydrogenated amorphous silicon layer, a p-type hydrogenated amorphous silicon layer, an aluminum oxide passivation layer, a P-conductive layer, and a metal electrode in sequence along the direction away from the front side of the N-type crystalline silicon substrate.

[0048] In some embodiments, an aluminum oxide passivation layer is disposed on the exposed silicon substrate surface at the interval between the N region and the P region.

[0049] In another specific embodiment, the present invention provides a method for preparing a BC battery as described in the foregoing specific embodiment, the method comprising: depositing transparent conductive oxides in an N-region and a P-region respectively using argon and oxygen as reaction gases; annealing to prepare an N-conductive layer in the N-region and a P-conductive layer in the P-region; and subjecting the N-conductive layer and the P-conductive layer to ozone treatment respectively.

[0050] This invention induces the formation of a denser high-oxidation-state metal oxide layer on the surface of the annealed transparent conductive oxide layer by ozone treatment. The formed high-oxidation-state metal oxide layer can form chemical bonds with base metal ions (for example, when the base metal is Cu, a Cu-O bond is formed), anchoring the base metal ions on the conductive layer surface. This better prevents the base metal ions from diffusing into the silicon substrate, reduces carrier recombination, and improves passivation contact.

[0051] In some embodiments, the volume ratio of argon to oxygen in the reaction gas is (10~30):1, for example, it can be 10:1, 12:1, 14:1, 16:1, 18:1, 20:1, 22:1, 24:1, 26:1, 28:1 or 30:1, including but not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0052] In some embodiments, the flow rate of the argon gas is 1000 sccm to 2000 sccm, for example, it can be 1000 sccm, 1200 sccm, 1400 sccm, 1600 sccm, 1800 sccm or 2000 sccm, including but not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0053] In some embodiments, the oxygen flow rate is 20 sccm to 100 sccm, for example, it can be 20 sccm, 40 sccm, 60 sccm, 80 sccm or 100 sccm, including but not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0054] In some embodiments, the ozone treatment includes treating the N-conductive layer and the P-conductive layer with an ozone solution of 3wt% to 8wt%. The concentration of the ozone solution may be, for example, 3wt%, 4wt%, 5wt%, 6wt%, 7wt%, or 8wt%, including but not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0055] In some embodiments, the ozone treatment time is 180s to 250s, for example, it can be 180s, 190s, 200s, 210s, 220s, 230s, 240s or 250s, including but not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0056] In some embodiments, the deposition pressure is 10. -4 Pa~10 -2 Pa, for example, could be 10. -4 Pa, 2×10 - 4 Pa, 3×10 -4 Pa, 4×10 -4 Pa, 5×10 -4 Pa, 6×10 -4 Pa, 7×10 -4 Pa, 8×10 -4 Pa, 9×10 -4 Pa, 10 -3 Pa, 2×10 -3 Pa, 3×10 -3 Pa, 4×10 -3 Pa, 5×10 -3 Pa, 6×10 -3 Pa, 7×10 -3 Pa, 8×10 -3 Pa, 9×10 -3 Pa or 10 -2 Pa, including but not limited to the listed values, and other unlisted values ​​within the range also apply.

[0057] In some embodiments, the deposition temperature is 20°C to 200°C, for example, it can be 20°C, 40°C, 60°C, 80°C, 100°C, 120°C, 140°C, 160°C, 180°C or 200°C, including but not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0058] In some embodiments, the water vapor partial pressure is ≤1.0×10⁻⁶ during the deposition process. -3 Pa, for example, could be 0.1 × 10⁻⁶. -3 Pa, 0.2×10 -3 Pa, 0.3×10 -3 Pa, 0.4×10 -3 Pa, 0.5×10 -3 Pa, 0.6×10 -3 Pa, 0.7×10 - 3 Pa, 0.8×10-3 Pa, 0.9×10 -3 Pa or 1.0 × 10 -3 Pa, including but not limited to the listed values, and other unlisted values ​​within the range also apply.

[0059] In some embodiments, the annealing temperature is 160°C to 200°C, for example, it can be 160°C, 165°C, 170°C, 175°C, 180°C, 185°C, 190°C, 195°C or 200°C, including but not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0060] In some embodiments, the annealing time is 30 min to 100 min, for example, it can be 30 min, 40 min, 50 min, 60 min, 70 min, 80 min, 90 min or 100 min, including but not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0061] In some embodiments, the method of depositing the transparent conductive oxide includes any one of magnetron sputtering, evaporation, or ion plating.

[0062] In yet another embodiment, the present invention provides a photovoltaic module comprising a BC cell as described in the preceding embodiment.

[0063] To clearly illustrate the technical solution of this invention, the preparation process of the BC battery in this invention includes:

[0064] (1) A tunneling layer and a polycrystalline silicon layer are prepared on the front and back sides of the polished N-type crystalline silicon substrate, respectively, and phosphorus diffusion is performed to form PSG;

[0065] (2) A silicon nitride layer is deposited on the PSG surface on the back side, and a laser process is used to create grooves in the P region and the gap region between the N region and the P region on the surface of the silicon nitride layer.

[0066] (3) Remove the PSG on the front side and texturize it; remove the PSG and tunneling layer in the P area and the Gap area;

[0067] (4) Deposit an intrinsic hydrogenated amorphous silicon layer and a silicon nitride antireflection layer on the textured surface on the front side;

[0068] (5) An intrinsic hydrogenated amorphous silicon layer and a p-type hydrogenated amorphous silicon layer are deposited sequentially on the back side; the intrinsic hydrogenated amorphous silicon layer, the p-type hydrogenated amorphous silicon layer and the silicon nitride layer on the surface of the N region are removed by laser removal process; and the intrinsic hydrogenated amorphous silicon layer and the p-type hydrogenated amorphous silicon layer on the surface of the Gap region are removed to form a texturing layer.

[0069] (6) An aluminum passivation layer is deposited on the back side, and an N-conductive layer is prepared on the surface of the aluminum passivation layer in the N region, and a P-conductive layer is prepared on the surface of the aluminum passivation layer in the P region.

[0070] (7) Metal electrodes are prepared on the surface of the N conductive layer and the surface of the P conductive layer respectively to obtain the BC battery.

[0071] Those skilled in the art can also make reasonable selections and adjustments to the process of BC batteries according to their needs.

[0072] Example 1

[0073] This embodiment provides a BC battery, wherein the conductive electrodes of the BC battery are made of copper; such as Figure 1 As shown, the BC battery includes an N-type crystalline silicon substrate, which has a front side and a back side facing each other. The back side of the N-type crystalline silicon substrate includes N-regions, Gap regions, and P-regions arranged in a crisscross pattern. In the N-regions, along the direction away from the front side of the N-type crystalline silicon substrate, a tunneling oxide layer 3, an n-type polycrystalline silicon doped layer 4, an aluminum oxide passivation layer 5, an N-conductive layer 9, and a metal electrode 7 are sequentially disposed. In the P-regions, along the direction away from the front side of the N-type crystalline silicon substrate, an intrinsic hydrogenated amorphous silicon layer 2, a p-type hydrogenated amorphous silicon layer 8, an aluminum oxide passivation layer 5, a P-conductive layer 6, and a metal electrode 7 are sequentially disposed. On the front side of the N-type crystalline silicon substrate, along the direction away from the back side, an intrinsic hydrogenated amorphous silicon layer 2 and a silicon nitride antireflection layer 1 are sequentially disposed. An aluminum oxide passivation layer 5 is disposed on the surface of the N-type crystalline silicon substrate in the Gap region.

[0074] The carrier concentrations in the N-conductive layer 9 and the P-conductive layer 6 are 1.5 × 10⁻⁶ and 1.5 × 10⁻⁶, respectively. 20 cm -3 and 3.0×10 20 cm -3 The carrier mobilities in the N-conductive layer 9 and the P-conductive layer 6 are 75 cm⁻¹, respectively. 2 ·V -1 ·s -1 and 60cm 2 ·V -1 ·s -1 The N-conductive layer 9 and the P-conductive layer 6 are respectively 50 nm indium tin oxide layers and 70 nm indium tin oxide layers.

[0075] This embodiment also provides a method for preparing a BC battery, including:

[0076] Argon gas at 1200 sccm and oxygen gas at 60 sccm were used as reactants, and the partial pressure of water vapor was controlled at 1.0 × 10⁻⁶. -3 Pa, deposition pressure is 8 × 10 -3At a deposition temperature of 150 °C, a 55 nm indium tin oxide layer and an 85 nm tungsten-doped indium tin oxide layer were deposited in the N region and the P region, respectively. The layers were annealed at 180 °C for 50 min and then treated with a 5 wt% ozone solution for 200 s to prepare an N-conductive layer 9 in the N region and a P-conductive layer 6 in the P region.

[0077] Example 2

[0078] This embodiment provides a BC battery. Compared to Embodiment 1, the BC battery differs in that the conductive electrode is made of aluminum, and the carrier concentrations in the N-conductive layer and P-conductive layer are 2.0 × 10⁻⁶. 20 cm -3 and 3.0×10 20 cm -3 The carrier mobilities in the N-conductive layer and the P-conductive layer are 65 cm⁻¹, respectively. 2 ·V -1 ·s -1 and 60cm 2 ·V -1 ·s -1 Except for the N-conductive layer being a 70nm tungsten-doped indium tin oxide layer and the P-conductive layer being a 45nm indium tin oxide layer, the rest are the same as in Example 1.

[0079] This embodiment also provides a method for preparing a BC battery, including:

[0080] Using 2000 sccm of argon and 80 sccm of oxygen as the reactants, the partial pressure of water vapor was controlled at 0.3 × 10⁻⁶. -3 Pa, deposition pressure is 10 -4 At a deposition temperature of 20 °C, 70 nm tungsten-doped indium tin oxide (ITO) layers and 45 nm ITO layers were deposited in the N and P regions, respectively. The layers were annealed at 160 °C for 30 min and then treated with 3 wt% ozone solution for 180 s to prepare an N-conductive layer in the N region and a P-conductive layer in the P region.

[0081] Example 3

[0082] This embodiment provides a BC battery, which, compared to Embodiment 1, has carrier concentrations of 1.5 × 10⁻⁶ in both the N-conductive layer and the P-conductive layer. 20 cm -3 and 2.0×10 20 cm -3 The carrier mobilities in the N-conductive layer and the P-conductive layer are 75 cm⁻¹, respectively. 2 ·V -1 ·s -1 and 65cm 2 ·V -1 ·s-1 Except for the N-conductive layer being a 100nm tungsten-doped indium tin oxide layer and the P-conductive layer being an 80nm indium tin oxide layer, the rest are the same as in Example 1.

[0083] This embodiment also provides a method for preparing a BC battery, including:

[0084] Using 1000 sccm of argon and 50 sccm of oxygen as the reaction gases, the partial pressure of water vapor was controlled at 0.8 × 10⁻⁶. -3 Pa, deposition pressure is 10 -2 At a deposition temperature of 200℃, 70 nm tungsten-doped indium tin oxide (ITO) layers and 100 nm ITO layers were deposited in the N and P regions, respectively. The layers were annealed at 200℃ for 100 min and then treated with 3 wt% ozone solution for 240 s to prepare an N-conductive layer in the N region and a P-conductive layer in the P region.

[0085] Example 4

[0086] This embodiment provides a BC battery, which is the same as that in Example 1 except that it is treated with 8wt% ozone solution during the preparation process.

[0087] Example 5

[0088] This embodiment provides a BC battery, which is the same as that in Example 1 except that ozone treatment with 2wt% ozone solution is used in the preparation process.

[0089] Example 6

[0090] This embodiment provides a BC battery, which is the same as that in Example 1 except that ozone treatment with 10wt% ozone solution is used in the preparation process.

[0091] Example 7

[0092] This embodiment provides a BC battery, except that the deposition pressure during the preparation process is 0.5 × 10⁻⁶. -4 Except for Pa, everything else is the same as in Example 1.

[0093] Example 8

[0094] This embodiment provides a BC battery, except that the deposition pressure during the preparation process is 2×10⁻⁶. -2 Except for Pa, everything else is the same as in Example 1.

[0095] Example 9

[0096] This embodiment provides a BC battery, except that the water vapor partial pressure is 1.2 × 10⁻⁶ during the manufacturing process. -3 Except for Pa, everything else is the same as in Example 1.

[0097] Example 10

[0098] This embodiment provides a BC battery, which is the same as that in Example 1 except that the annealing temperature is 140°C during the preparation process.

[0099] Example 11

[0100] This embodiment provides a BC battery, which is the same as that in Embodiment 1 except that the annealing temperature is 220°C during the preparation process.

[0101] Comparative Example 1

[0102] This comparative example provides a BC battery, except that the carrier concentrations in the N-conductive layer and the P-conductive layer are 3.0 × 10⁻⁶ respectively. 20 cm -3 and 2.5×10 20 cm -3 The carrier mobilities in the N-conductive layer and the P-conductive layer are 50 cm⁻¹, respectively. 2 ·V -1 ·s -1 and 60cm 2 ·V -1 ·s -1 Except for the above, everything else is the same as in Example 1.

[0103] Comparative Example 2

[0104] This comparative example provides a BC battery, wherein the carrier concentration in both the N-conductive layer and the P-conductive layer is 2.5 × 10⁻⁶. 20 cm -3 The carrier mobility in both the N-conductive layer and the P-conductive layer is 60 cm⁻¹. 2 ·V -1 ·s -1 Except for the above, everything else is the same as in Example 1.

[0105] Performance testing:

[0106] IV tests were performed on the BC batteries provided in all the above embodiments and comparative examples. The batteries used in the tests were 182 half-cell batteries with a test area of ​​19137 mm². 2 The photoelectric conversion efficiency Eta, open-circuit voltage Voc, short-circuit current Isc, and fill factor FF of the battery were tested. The test results are shown in Table 1.

[0107] Table 1

[0108]

[0109] Based on the test results of Examples 1 to 4 in Table 1, the present invention, by setting a P conductive layer with a higher carrier concentration in the P region and an N conductive layer with a lower carrier concentration in the N region of the interdigitated BC cell, can effectively reduce the ohmic contact between n-type polycrystalline silicon and p-type amorphous silicon and the metal paste, thereby increasing the current density and thus improving the photoelectric efficiency of the solar cell.

[0110] According to the test results of Example 1, Comparative Examples 1 and 2, if the carrier concentration of the N-conductive layer is not lower than that of the P-conductive layer, it is impossible to simultaneously and effectively reduce the ohmic contact between the n-type polycrystalline silicon and the p-type amorphous silicon and the metal paste, thus failing to increase the current density and resulting in a decrease in the photoelectric efficiency of the solar cell.

[0111] Based on the test results of Examples 1, 5, and 6, the concentration of ozone solution affects the density of the high oxidation state metal oxide layer induced on the TCO surface and the number of chemical bonds (such as Cu-O bonds) formed between the oxide and copper ions. If the concentration of ozone solution is too low (Example 5), the oxidation is incomplete, and the formed oxide layer cannot anchor copper ions on the TCO surface. Copper ions will continue to diffuse to the silicon substrate. If the concentration of ozone solution is too high (Example 6), the unstable oxygen-oxygen bonds (bond energy of about 106 kJ / mol) in the molecule are easily decomposed into O2 and reactive oxygen species (such as ·O free radicals). Their oxidation activity is greatly reduced and cannot prevent the diffusion of copper ions. Both of these results in unsatisfactory performance improvement of solar cells.

[0112] Based on the test results of Examples 1, 7, and 8, the deposition pressure affects the mean free path of gas molecules. Target particles (such as In, Sn, or Zn) generated by low-pressure sputtering collide less before reaching the substrate, retaining higher kinetic energy (typically hundreds of eV), resulting in strong diffusion and easy formation of a dense film layer with fewer lattice defects (refer to Example 1). High-pressure sputtering (Example 8) results in a short mean free path of gas molecules, significantly reducing the kinetic energy of particles after multiple collisions. Excessively low pressure (Example 7) also significantly reduces kinetic energy, leading to weak diffusion upon reaching the substrate and easy formation of loose aggregates. This reduces the conductivity of the conductive film layer and increases its sheet resistance, both of which result in unsatisfactory performance improvements in solar cells.

[0113] Based on the test results of Examples 1 and 9, if the partial pressure of water vapor is greater than 1.0 × 10⁻⁶, -3 Pa, by refining grains, increasing grain boundary density and introducing impurity defects, intensifies scattering, leading to a significant decrease in mobility; it also provides excess oxygen to suppress oxygen vacancies, reduces doping activation rate and forms deep level traps, resulting in a sharp drop in carrier concentration, which also leads to unsatisfactory performance improvement of solar cells.

[0114] Based on the test results of Examples 1, 10, and 11, magnetron sputtered TCO films (such as ITO and AZO) typically exhibit metastable characteristics such as lattice distortion, dense defects (vacancies, dislocations), and small grains, resulting in suboptimal electrical performance. Annealing achieves this through thermal activation: reducing surface energy, promoting the merging of small grains into larger grains, and reducing the number of grain boundaries; it can also optimize the distribution of oxygen vacancies (the main source of charge carriers) through vacancy migration and dislocation annihilation to repair and reorganize defects; and it encourages doped atoms (such as Sn in ITO and Al in AZO) to enter lattice substitution sites, improving electron donation efficiency. If the annealing temperature is too high (Example 11), it will lead to uneven thermal expansion of the lattice, causing new dislocations and stress defects, and re-enhancing defect scattering. If the annealing temperature is too low (Example 10), the grains will not grow significantly, the grain boundary density will remain high, and the improvement in mobility will be limited, which will also result in an insignificant improvement in the performance of the solar cell.

[0115] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A BC battery, characterized in that, The conductive electrodes of the BC battery are made of base metals; The BC cell includes an N-type crystalline silicon substrate, the N-type crystalline silicon substrate having opposing front and back sides, the back side of the N-type crystalline silicon substrate having N-regions and P-regions arranged in a cross pattern but not in contact; The N region is provided with an N conductive layer, the P region is provided with a P conductive layer, and the carrier concentration of the N conductive layer is lower than that of the P conductive layer. The carrier concentrations in the N-layer and P-layer are each independently 1.0 × 10⁻⁶. 20 cm -3 ~3.0×10 20 cm -3 ; The carrier mobility in the N-conductive layer and the P-conductive layer is independently 30 cm⁻¹. 2 ·V -1 ·s -1 ~130cm 2 ·V -1 ·s -1 ; The materials of the P-conductive layer and the N-conductive layer each independently include indium tin oxide or tungsten-doped indium tin oxide; The N-conductive layer and the P-conductive layer are respectively treated with ozone.

2. The BC battery as described in claim 1, characterized in that, On the front side of the N-type crystalline silicon substrate, a hydrogenated amorphous silicon layer and a silicon nitride antireflection layer are sequentially disposed in the direction away from the back side. And / or, the N region is provided with a tunneling oxide layer, an n-type polycrystalline silicon doped layer, an aluminum oxide passivation layer, an N-conductive layer and a metal electrode in sequence along the direction away from the front side of the N-type crystalline silicon substrate; And / or, the P region is provided with an intrinsic hydrogenated amorphous silicon layer, a p-type hydrogenated amorphous silicon layer, an aluminum oxide passivation layer, a P-conductive layer and a metal electrode in sequence along the direction away from the front side of the N-type crystalline silicon substrate; And / or, an aluminum oxide passivation layer is provided on the exposed silicon substrate surface at the interval between the N region and the P region.

3. A method for preparing a BC battery as described in claim 1 or 2, characterized in that, The preparation method includes: Using argon and oxygen as reactants, transparent conductive oxides are deposited in the N-region and P-region, respectively; annealing is then performed to prepare an N-conductive layer in the N-region and a P-conductive layer in the P-region. The N-conductive layer and the P-conductive layer are respectively subjected to ozone treatment.

4. The preparation method according to claim 3, characterized in that, The ozone treatment includes treating the N-conductive layer and the P-conductive layer with an ozone solution of 3wt% to 8wt%. And / or, the ozone treatment time is 180s~250s.

5. The preparation method according to claim 3, characterized in that, The deposition pressure is 10. -4 Pa~10 -2 Pa; And / or, the deposition temperature is 20°C to 200°C.

6. The preparation method according to claim 3, characterized in that, During the deposition process, the partial pressure of water vapor is ≤1.0×10⁻⁶. -3 Pa.

7. The preparation method according to claim 3, characterized in that, The annealing temperature is 160℃~200℃; And / or, the annealing time is 30 min to 100 min.

8. The preparation method according to claim 3, characterized in that, The method of depositing transparent conductive oxides includes any one of magnetron sputtering, evaporation, or ion plating.

9. A photovoltaic module, characterized in that, The photovoltaic module includes the BC cell as described in claim 1 or 2.

Images