CN219246693U - Double-sided solar cell - Google Patents
Double-sided solar cell Download PDFInfo
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- CN219246693U CN219246693U CN202222427688.4U CN202222427688U CN219246693U CN 219246693 U CN219246693 U CN 219246693U CN 202222427688 U CN202222427688 U CN 202222427688U CN 219246693 U CN219246693 U CN 219246693U
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Abstract
The utility model discloses a bifacial solar cell, and relates to the field of crystalline silicon solar cells. Specifically, the bifacial solar cell comprises a top cell, a silicon substrate, a tunneling layer and a bottom cell, wherein the top cell is arranged above the substrate, the bottom cell is arranged below the substrate, and the tunneling layer is arranged between the substrate and the bottom cell; the bottom cell is a homojunction cell composed of a p-type germanium film and an n-type germanium film. The homojunction battery composed of the germanium thin films is introduced into the double-sided solar battery, the absorption wavelength of the solar battery can be expanded from about 1100nm to about 1800nm, the light utilization rate of the solar battery is greatly improved, and the conversion efficiency of the solar battery is further improved.
Description
Technical Field
The utility model relates to the field of crystalline silicon solar cells, in particular to a bifacial solar cell.
Background
Existing high efficiency solar cells are typically n-type monocrystalline silicon substrate crystalline silicon based solar cells, typically n-type HJT, TOPCon or IBC cells. The solar cells are single junction solar cells, and the solar cells are prepared by adopting silicon materials as the cell structures, so that the performances of the prepared solar cells are limited by the electrical and optical performances of the silicon materials, the spectrum of solar incident light is difficult to fully utilize, and the conversion efficiency is greatly limited. Specifically, since the intrinsic forbidden bandwidth of the silicon material is about 1.12eV, the crystalline silicon and the amorphous silicon material are not substantially absorbed for long-wavelength light, especially for infrared wavelength with wavelength greater than 1100nm, so that the silicon-based single-junction cell has low solar light utilization rate, and has low photoelectric conversion efficiency due to the steep decrease of the visible light duty ratio under the weak light condition.
Disclosure of Invention
The utility model aims to solve the technical problem of providing a double-sided solar cell, which can widen the wavelength range of absorbed light, improve the utilization efficiency of the light and further improve the conversion efficiency of the light.
In order to solve the technical problems, the utility model provides a bifacial solar cell, which comprises a top cell, a silicon substrate, a tunneling layer and a bottom cell, wherein the top cell is arranged above the substrate, the bottom cell is arranged below the substrate, and the tunneling layer is arranged between the substrate and the bottom cell;
the bottom cell is a homojunction cell composed of a p-type germanium film and an n-type germanium film.
As an improvement of the technical scheme, the thickness of the p-type germanium film is 20-40 nm, and the thickness of the n-type germanium film is 30-50 nm.
As an improvement of the above technical solution, the tunneling layer includes an n-type heavily doped amorphous silicon layer disposed near the silicon substrate and a p-type heavily doped amorphous silicon layer disposed near the bottom cell.
As an improvement of the technical scheme, the thickness of the n-type heavily doped amorphous silicon layer is 5-15 nm;
the thickness of the p-type heavily doped amorphous silicon layer is 5-15 nm.
As an improvement of the technical scheme, a buffer layer is arranged between the tunneling layer and the silicon substrate, the buffer layer is made of intrinsic amorphous silicon, and the thickness of the buffer layer is 2-8 nm.
As an improvement of the above technical solution, the p-type germanium film is disposed close to the p-type heavily doped amorphous silicon layer, and the n-type germanium film is disposed away from the p-type heavily doped amorphous silicon layer.
As an improvement of the technical scheme, the solar cell further comprises a first anti-reflection layer and a back electrode which are sequentially arranged on the bottom cell, wherein the thickness of the first anti-reflection layer is 90-110 nm.
As an improvement of the technical scheme, the silicon substrate is an n-type monocrystalline silicon substrate, and an intrinsic amorphous silicon layer and a p-type amorphous silicon layer are arranged above the silicon substrate;
the n-type monocrystalline silicon substrate, the intrinsic amorphous silicon layer and the p-type amorphous silicon layer form a heterojunction top-layer cell.
As an improvement of the technical scheme, the thickness of the intrinsic amorphous silicon layer is 2-8 nm, and the thickness of the p-type amorphous silicon layer is 5-20 nm.
As an improvement of the technical scheme, the amorphous silicon anode further comprises a second anti-reflection layer and a positive electrode which are sequentially arranged on the p-type amorphous silicon layer, wherein the thickness of the second anti-reflection layer is 70-90 nm.
The implementation of the utility model has the following beneficial effects:
1. the double-sided solar cell comprises a top cell, a silicon substrate, a tunneling layer and a bottom cell, wherein the bottom cell is a homojunction cell consisting of a p-type germanium film and an n-type germanium film. The absorption cut-off wavelength of the bifacial solar cell can be expanded from about 1100nm to about 1800nm due to the wider forbidden bandwidth of Ge, so that the light utilization rate of the bifacial solar cell is greatly improved, and the conversion efficiency of the solar cell, especially under the condition of weak light, is improved.
2. The double-sided solar cell adopts the n-type heavily doped amorphous silicon layer and the p-type heavily doped amorphous silicon layer to form the tunneling layer together, and is used for connecting the germanium cell and the top cell at the bottom layer, the tunneling layer has good connection effect, the absorption of light can be reduced, and the conversion efficiency of the double-sided solar cell is further improved.
Drawings
Fig. 1 is a schematic structural diagram of a double-sided solar cell according to an embodiment of the present utility model.
Detailed Description
The present utility model will be described in further detail with reference to the accompanying drawings, for the purpose of making the objects, technical solutions and advantages of the present utility model more apparent.
The present embodiment provides a bifacial solar cell comprising a bottom cell 1, a tunneling layer 2, a substrate 3 and a top cell 4, which are stacked in this order. Specifically, the bottom cell 1 includes a p-type germanium film 11 and an n-type germanium film 12, which together form a homojunction cell. The tunneling layer 2 is used to turn on the bottom cell 1 and the top cell 4. The top battery 4 may be an IBC battery or an HBC battery, but is not limited thereto. Based on the structure, the double-junction double-sided solar cell is formed, wherein the germanium cell formed by the p-type germanium film 11 and the n-type germanium film 12 can expand the absorption cut-off wavelength of the double-sided solar cell from about 1100nm to about 1800nm, so that the light utilization rate of the double-sided solar cell is greatly improved, and the conversion efficiency of the solar cell, particularly the conversion efficiency under the weak light condition, is improved.
Specifically, in the present embodiment, the p-type germanium film 11 is disposed close to the tunneling layer 2. The thickness of the p-type germanium film 11 is 20 to 40nm, and is exemplified by 22nm, 24nm, 26nm, 28nm, 32nm, 35nm, or 38nm, but is not limited thereto. Preferably 30nm. The doping element of the p-type germanium film 11 is B or Al, but is not limited thereto. Preferably, the doping element of the p-type germanium film 11 is B. The p-type germanium film 11 may be formed by a Ge-containing gas (e.g., geH 4 Etc.), doping element gas deposition. Exemplary, in one embodiment, a PECVD apparatus is used to fabricate p-type germanium film 11 having a deposition temperature of 200-400℃, geH 4 The flow is 600 sccm-1500 sccm, BH 3 The flow rate is 250 sccm-500 sccm, the radio frequency power is 4000 w-8000 w, and the deposition time is 170 s-320 s, but is not limited to this.
Specifically, in the present embodiment, the n-type germanium film 12 is disposed away from the tunneling layer 2. The thickness of the n-type germanium film 12 is 30 to 50nm, and is exemplified by, but not limited to, 32nm, 34nm, 36nm, 38nm, 42nm, 45nm, or 48 nm. Preferably, the n-type germanium film 12 has a thickness of 30nm. The doping element of the n-type germanium film 12 is P or As, but is not limited thereto; preferably P. The n-type germanium film 12 may be formed by a Ge-containing gas (e.g., geH 4 Etc.), doping element gas deposition. Exemplary, in one embodiment, the n-type germanium film 12 is prepared using a PECVD apparatus, the deposition temperature is 200-400 ℃, geH 4 The flow is 800 sccm-1800 sccm, and the PH value is the same 3 The flow rate is 300 sccm-600 sccm, the radio frequency power is 4000 w-8000 w, and the deposition time is 150 s-350 s, but is not limited to this.
Specifically, in the present embodiment, the bottom cell 1 further includes a first anti-reflection layer 13 and a back electrode 14 sequentially provided on the n-type germanium film 12. Among them, the first anti-reflection layer 13 is made of silicon nitride, TCO, or the like, but is not limited thereto. The thickness of the first anti-reflection layer 13 is 90 to 110nm, and is exemplified by 93nm, 96nm, 99nm, 102nm, 105nm, or 108nm, but is not limited thereto. The first anti-reflection layer 13 may be prepared by magnetron sputtering or reactive plasma deposition, but is not limited thereto.
The back electrode 14 may be a gate line structure or a thin film structure, which is common in the art, but is not limited thereto. Preferably, the back electrode 14 is a gate line structure, and the width of a single gate line is 30-70 μm. The back electrode 14 may be a silver electrode, an aluminum electrode, but is not limited thereto. The back electrode may be prepared by a screen printing process.
Wherein the tunneling layer 2 can be SiO 2 Layer, h-BN layer, but are not limited thereto. Preferably, in the present embodiment, the tunneling layer 2 includes an n-type heavily doped amorphous silicon layer 21 disposed close to the silicon substrate 3 and a p-type heavily doped amorphous silicon layer 22 disposed close to the bottom cell 1. The tunneling layer 2 has less light absorption and high light transmittance, and further improves the photoelectric conversion efficiency of the bifacial solar cell.
Specifically, the thickness of the n-type heavily doped amorphous silicon layer 21 is 5 to 15nm, and is exemplified by 6nm, 8nm, 10nm, 12nm, or 14nm, but is not limited thereto. Preferably, the thickness of the n-type heavily doped amorphous silicon layer 21 is 10nm. Specifically, the n-type heavily doped amorphous silicon layer 21 has a doping element of P with a doping concentration of 1×10 20 ～3×10 20 cm -3 . The n-type heavily doped amorphous silicon layer 21 may be formed by a Si-containing gas (e.g., siH 4 Etc.), doping element gas deposition. Exemplary, in one embodiment, the n-type heavily doped amorphous silicon layer 21 is prepared using a PECVD apparatus, the deposition temperature is 200 ℃ to 400 ℃, siH 4 The flow rate is 500sccm to 1000sccm, and the PH value is 3 The flow is 100 sccm-300 sccm, the radio frequency power is 3000 w-6000 w, and the deposition time is 100 s-200 s.
Specifically, the thickness of the p-type heavily doped amorphous silicon layer 22 is 5 to 15nm, and exemplary is 6nm, 8nm, 10nm, 12nm or 14nm, but is not limited thereto. Preferably, the thickness of the p-type heavily doped amorphous silicon layer 22 is 10nm. Specifically, the doping element of the p-type heavily doped amorphous silicon layer 22 isB, the doping concentration is 2×10 20 ～4×10 20 cm -3 . The p-type heavily doped amorphous silicon layer 22 may be formed by a Si-containing gas (e.g., siH 4 Etc.), doping element gas deposition. Illustratively, in one embodiment, the p-type heavily doped amorphous silicon layer 22 is prepared using a PECVD apparatus at a deposition temperature of 200-400℃ SiH 4 Flow rate is 500 sccm-1000 sccm, BH 3 The flow is 200 sccm-300 sccm, the radio frequency power is 3000 w-6000 w, and the deposition time is 150 s-250 s.
Specifically, in the present embodiment, a buffer layer 5 is disposed between the tunneling layer 2 and the silicon substrate 3, which can effectively reduce the interfacial recombination between the n-type heavily doped amorphous silicon layer 21 and the silicon substrate 3. Specifically, the buffer layer 5 is made of intrinsic amorphous silicon, and has a thickness of 2 to 8nm. Specifically, the buffer layer 5 may be prepared by a PECVD method. Specifically, in one embodiment, the deposition temperature of the buffer layer 5 is 200 ℃ to 400 ℃, siH 4 The flow is 500 sccm-1000 sccm, the radio frequency power is 3000 w-6000 w, and the deposition time is 50 s-150 s. In addition, the tunneling layer 2 and the buffer layer 5 are prepared in the same PECVD equipment.
Specifically, the silicon substrate 3 may be a P-type single crystal silicon substrate or an N-type single crystal silicon substrate, but is not limited thereto. The silicon substrate 3 is formed with a double sided pyramid suede structure during solar cell fabrication.
Specifically, the top cell 4 includes an intrinsic amorphous silicon layer 41 and a p-type amorphous silicon layer 42 sequentially provided on the front surface of the silicon substrate 3, and the n-type single crystal silicon substrate 3, the intrinsic amorphous silicon layer 41, and the p-type amorphous silicon layer 42 together constitute a heterojunction silicon cell. Further, a second anti-reflection layer 43 and a positive electrode 44 are sequentially provided on the p-type amorphous silicon layer 42.
Specifically, in the present embodiment, the thickness of the intrinsic amorphous silicon layer 41 is 2 to 8nm, and is exemplified by 3nm, 4nm, 5nm, 6nm, or 7nm, but is not limited thereto. Specifically, the intrinsic amorphous silicon layer 41 may be prepared by a PECVD method. Specifically, in one embodiment, the deposition temperature of intrinsic amorphous silicon layer 41 is 200-400 ℃ and SiH 4 The flow is 500 sccm-1000 sccm, the radio frequency power is 2000 w-5000 w, and the deposition time is 50 s-130 s.
Specifically, in the present embodiment, the thickness of the p-type amorphous silicon layer 42 is 5 to 20nm; exemplary are, but not limited to, 7nm, 9nm, 10nm, 12nm or 14 nm. Preferably, the thickness of the p-type amorphous silicon layer 42 is 10nm, which can be made by a PECVD method. Specifically, in one embodiment, the deposition temperature of the p-type amorphous silicon layer 42 is 200 ℃ to 400 ℃, siH 4 The flow is 500 sccm-1000 sccm, BH 3 The flow is 100 sccm-300 sccm, the radio frequency power is 3000 w-6000 w, and the deposition time is 70 s-150 s.
Specifically, in the present embodiment, the second anti-reflection layer 43 is made of silicon nitride, TCO, or the like, but is not limited thereto. The thickness of the second anti-reflection layer 43 is 70 to 90nm, and is exemplified by 73nm, 76nm, 79nm, 82nm, 85nm, or 88nm, but is not limited thereto. The second anti-reflection layer 43 may be prepared by magnetron sputtering or reactive plasma deposition, but is not limited thereto.
Positive electrode 44 may be, but is not limited to, a grid-like structure as is common in the art, or a thin film structure. Preferably, the positive electrode 44 is a grid line structure, and the width of a single grid line is 25-50 μm. The positive electrode 44 may be a silver electrode, an aluminum electrode, but is not limited thereto. The positive electrode can be prepared by a screen printing process.
Specifically, the preparation method of the bifacial solar cell in this embodiment is as follows:
(1) Providing a silicon substrate, and carrying out double-sided cleaning and double-sided texturing on the silicon substrate;
(2) Forming a buffer layer 5, an n-type heavily doped amorphous silicon layer 21, a p-type heavily doped amorphous silicon layer 22, a p-type germanium film 11, an n-type germanium film 12 and a first anti-reflection layer 13 on the back of the silicon substrate after flocking;
(3) Sequentially forming an intrinsic amorphous silicon layer 41, a p-type amorphous silicon layer 42 and a second anti-reflection layer 43 on the front surface of the silicon substrate obtained in the step (2);
(4) Printing a front electrode and a back electrode, and sintering.
The foregoing description is only a preferred embodiment of the present utility model, and it is not intended to limit the scope of the claims, so that the equivalent changes of the claims are included in the scope of the present utility model.
Claims (10)
1. The double-sided solar cell is characterized by comprising a top cell, a silicon substrate, a tunneling layer and a bottom cell, wherein the top cell is arranged above the substrate, the bottom cell is arranged below the substrate, and the tunneling layer is arranged between the substrate and the bottom cell;
the bottom cell is a homojunction cell composed of a p-type germanium film and an n-type germanium film.
2. The bifacial solar cell according to claim 1, wherein the thickness of the p-type germanium film is 20-40 nm and the thickness of the n-type germanium film is 30-50 nm.
3. The bifacial solar cell of claim 1 wherein said tunneling layer comprises an n-type heavily doped amorphous silicon layer disposed adjacent said silicon substrate and a p-type heavily doped amorphous silicon layer disposed adjacent said bottom cell.
4. The bifacial solar cell according to claim 3, wherein the thickness of said n-type heavily doped amorphous silicon layer is 5-15 nm;
the thickness of the p-type heavily doped amorphous silicon layer is 5-15 nm.
5. The bifacial solar cell according to claim 1, wherein a buffer layer is arranged between said tunneling layer and said silicon substrate, and is made of intrinsic amorphous silicon and has a thickness of 2-8 nm.
6. The bifacial solar cell of claim 4 wherein said p-type germanium film is disposed adjacent to said p-type heavily doped amorphous silicon layer and said n-type germanium film is disposed away from said p-type heavily doped amorphous silicon layer.
7. The bifacial solar cell according to claim 1, further comprising a first anti-reflection layer and a back electrode sequentially arranged on said bottom cell, wherein the thickness of said first anti-reflection layer is 90-110 nm.
8. The bifacial solar cell according to claim 1, wherein said silicon substrate is an n-type monocrystalline silicon substrate having an intrinsic amorphous silicon layer and a p-type amorphous silicon layer disposed thereon;
the n-type monocrystalline silicon substrate, the intrinsic amorphous silicon layer and the p-type amorphous silicon layer form a heterojunction top-layer cell.
9. The bifacial solar cell according to claim 8, wherein said intrinsic amorphous silicon layer has a thickness of 2-8 nm and said p-type amorphous silicon layer has a thickness of 5-20 nm.
10. The bifacial solar cell according to claim 8, further comprising a second anti-reflection layer and a positive electrode sequentially arranged on said p-type amorphous silicon layer, wherein the thickness of said second anti-reflection layer is 70-90 nm.
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| CN202222427688.4U CN219246693U (en) | 2022-09-13 | 2022-09-13 | Double-sided solar cell |
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| CN202222427688.4U CN219246693U (en) | 2022-09-13 | 2022-09-13 | Double-sided solar cell |
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