A heterojunction solar cell
By replacing the existing structure with a tunneling oxide layer and a P-type carbon-doped semiconductor stack in silicon-based heterojunction solar cells, the problems of high equipment cost and carrier transport loss are solved, thereby improving cell efficiency and reducing cost.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- GOLD STONE (FUJIAN) ENERGY CO LTD
- Filing Date
- 2022-09-30
- Publication Date
- 2026-05-12
AI Technical Summary
In the current production of silicon-based heterojunction solar cells, the equipment cost is high and the electrical power loss caused by the transport of charge carriers on the back of the cell is severe, which affects the cell efficiency.
By replacing the intrinsic amorphous silicon layer and the P-type doped amorphous layer with a tunneling oxide layer and a P-type carbon-doped semiconductor stack, and combining it with a P-type polycrystalline silicon stack, carrier transport is improved and infrared light absorption is reduced, thereby lowering equipment investment costs.
It significantly improves battery efficiency, reduces equipment costs, and enhances short-circuit current, open-circuit voltage, and fill factor by improving carrier transport and light absorption performance.
Smart Images
Figure CN117878177B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of solar cell technology, and relates to a heterojunction solar cell. Background Technology
[0002] With the continuous development of science and technology, solar cells have been widely used in people's daily lives and industry. In recent years, solar cell production technology has continued to advance, production costs have continued to decrease, and conversion efficiency has continued to increase. The application of solar cell power generation has become increasingly widespread and has become an important energy source for electricity supply.
[0003] Silicon-based heterojunction solar cells are a type of high-efficiency battery technology that combines the advantages of monocrystalline silicon solar cells and amorphous silicon solar cells. They have features such as higher conversion efficiency and better high-temperature characteristics, and therefore have great market potential.
[0004] Currently, the passivation and doping layers on the front and back sides of silicon-based heterojunction solar cells are deposited using plate-type plasma-enhanced chemical vapor deposition (PECVD) equipment. The deposition temperature is generally less than 220℃. To reduce cross-contamination of doping elements, silicon wafers are generally deposited sequentially with the following steps: intrinsic amorphous silicon layer on the back side, intrinsic amorphous silicon layer and N-type doped amorphous silicon layer on the front side, and P-type doped amorphous silicon layer on the back side. This requires the use of three sets of plate-type PECVD coating equipment, and the wafers need to enter and exit the vacuum chamber three times. The high equipment cost seriously hinders the development of heterojunction solar cells. Summary of the Invention
[0005] The purpose of this invention is to provide a heterojunction solar cell that improves electrical power loss caused by carrier transport on the back of the cell, thereby increasing cell efficiency.
[0006] The objective of this invention is achieved through the following technical solution:
[0007] A heterojunction solar cell includes a first electrode, a first conductive film, an N-type semiconductor film, an intrinsic film, a semiconductor substrate, a tunneling oxide layer, a P-type carbon-doped semiconductor film, a high-concentration P-type doped semiconductor film, a second conductive film, and a second electrode, which are sequentially stacked from the light-facing side to the back-facing side. The first conductive film completely covers the N-type semiconductor film, and the first electrode is electrically connected to the N-type semiconductor film through the first conductive film. The second conductive film completely covers the high-concentration P-type doped semiconductor film, and the second electrode is electrically connected to the high-concentration P-type doped semiconductor film through the second conductive film.
[0008] Compared with the prior art, the advantages of the present invention are as follows:
[0009] (1) The back of the battery uses a tunneling oxide layer and a P-type semiconductor stack (i.e., a P-type carbon-doped semiconductor film and a high-concentration P-type doped semiconductor film) to replace the intrinsic amorphous silicon layer and the P-type doped amorphous layer. The carrier mobility of the P-type semiconductor stack is significantly better than that of the P-type doped amorphous layer. Therefore, it can greatly improve the electrical power loss caused by the carrier transport on the back of the battery, thereby improving the battery efficiency.
[0010] (2) P-type polycrystalline silicon stack (i.e. P-type carbon-doped polycrystalline silicon layer, high-concentration P-type doped polycrystalline silicon layer) is adopted. The P-type carbon-doped polycrystalline silicon layer increases the band gap, which is beneficial to reduce the absorption of infrared light and increase the short-circuit current. The high-concentration P-type doped polycrystalline silicon layer increases the doping concentration, enhances the conductivity, which is beneficial to improve the carrier transport, and thus improves the fill factor and the cell conversion efficiency.
[0011] (3) The back of the battery uses a tunneling oxide layer and a P-type semiconductor stack to replace the intrinsic amorphous silicon layer and the P-type doped amorphous layer, which reduces the number of two sets of plate PECVD equipment, thereby significantly reducing the equipment investment cost. Attached Figure Description
[0012] Figure 1 This is a schematic diagram of the structure of Embodiment 1 of the present invention.
[0013] Figure 2 This is a schematic diagram of the structure of Embodiment 2 of the present invention.
[0014] Figure 3 This is a schematic diagram of the structure of Embodiment 3 of the present invention.
[0015] Figure 4 This is a schematic diagram of the structure of Embodiment 4 of the present invention.
[0016] Figure 5 This is a schematic diagram of the structure of Comparative Example 1.
[0017] Figure 6 This is a schematic diagram of the structure of one embodiment of the present invention.
[0018] Figure 7 This is a schematic diagram of a preferred embodiment of the present invention. Detailed Implementation
[0019] A heterojunction solar cell, characterized in that it comprises, in sequence from the light-facing side to the back-facing side, a first electrode, a first conductive film layer, an N-type semiconductor film layer, an intrinsic film layer, a semiconductor substrate, a tunneling oxide layer, a P-type carbon-doped semiconductor film layer, a high-concentration P-type doped semiconductor film layer, a second conductive film layer, and a second electrode; the first conductive film layer completely covers the N-type semiconductor film layer, and the first electrode is electrically connected to the N-type semiconductor film layer through the first conductive film layer; the second conductive film layer completely covers the high-concentration P-type doped semiconductor film layer, and the second electrode is electrically connected to the high-concentration P-type doped semiconductor film layer through the second conductive film layer.
[0020] The semiconductor substrate is a single-crystal silicon wafer, and the light-facing surface of the semiconductor substrate is provided with a pyramidal textured surface, the size of which is 1-10 μm.
[0021] The intrinsic film layer is an intrinsic amorphous silicon layer with a thickness of 3-12 nm; the N-type semiconductor film layer has a thickness of 9-20 nm.
[0022] The P-type carbon-doped semiconductor film is a P-type carbon-doped polycrystalline silicon layer, and the high-concentration P-type doped semiconductor film is a high-concentration P-type doped polycrystalline silicon layer.
[0023] The thickness of the tunneling oxide layer is 1-3 nm; the total thickness of the P-type carbon-doped polycrystalline silicon layer and the high-concentration P-type doped polycrystalline silicon layer is 100-250 nm, and the sheet resistance is 30-150 Ω / □. The thickness ratio of the P-type carbon-doped polycrystalline silicon layer to the high-concentration P-type doped semiconductor film is (1-3):5. In a preferred embodiment, the thickness of the P-type carbon-doped polycrystalline silicon layer is between 30-100 nm, and the sheet resistance is 70-150 Ω / □; the thickness of the high-concentration P-type doped semiconductor film is between 50-150 nm, and the sheet resistance is 30-70 Ω / □.
[0024] The phosphorus doping concentration of the N-type semiconductor film is 10. 19 -10 21 cm -3 The boron doping concentration of the P-type carbon-doped polycrystalline silicon layer is 10. 18 -10 20 cm -3 The carbon doping concentration is 10 18 -10 20 cm -3 The boron doping concentration of the high-concentration P-type doped semiconductor film is 10. 19 -10 21 cm -3 .
[0025] The first conductive film layer and / or the second conductive film layer are transparent conductive film layers or composite stacks of transparent conductive film layers and metal film layers.
[0026] The transparent conductive film layer is one or a combination of two or more of the following: indium tin oxide (ITO), tungsten-doped indium oxide (IWO), gallium-doped zinc-doped indium oxide (IGZO), aluminum-doped zinc oxide (AZO), zinc-doped indium oxide (IZO), gallium-doped zinc oxide (GZO), and titanium-doped indium oxide (ITiO); the material of the metal film layer is one or a combination of copper (Cu), silver (Ag), aluminum (Al), nickel alloy, gold (Au), indium tin oxide (ITO), aluminum-doped zinc oxide (AZO), and gallium-doped zinc oxide (GZO).
[0027] The thickness of the first conductive film layer is 50-70 nm; the thickness of the second conductive film layer is 30-150 nm, which is a transparent conductive film layer. In one embodiment, such as... Figure 6 As shown, the first conductive film layer 6N is a composite layer of a transparent conductive film layer 6N1 and a metal conductive layer 6N2, and the second conductive film layer 6P is a composite layer of a transparent conductive film layer 6P1 and a metal conductive layer 6P2; the transparent conductive film layers 6N1 and 6P1 are both indium tin oxide (ITO) and tungsten-doped indium oxide (IWO), with a thickness of 20-100 nm; the metal conductive layers 6N2 and 6P2 are both seed copper layers with a thickness of 50-150 nm. In a preferred embodiment, as... Figure 7 As shown, the first conductive film layer 6N is a transparent conductive film made of indium tin oxide (ITO) with a thickness of 70-110 nm; the second conductive film layer 6P is a composite layer of a transparent conductive film layer 6P1, a metal conductive layer 6P2, and a protective layer 6P3; the transparent conductive film layer 6P1 is either indium tin oxide (ITO) or tungsten-doped indium oxide (IWO) with a thickness of 20-100 nm; the metal conductive layer 6P2 is copper with a thickness of 100-500 nm; and the protective layer 6P3 is a nickel-chromium alloy with a thickness of 30-100 nm.
[0028] The N-type semiconductor film is an N-type microcrystalline stack; the N-type microcrystalline stack comprises one or more oxygen-containing microcrystalline layers and one or more oxygen-free microcrystalline layers.
[0029] The N-type microcrystalline stack includes an oxygen-free microcrystalline layer, an oxygen-containing microcrystalline layer, and an oxygen-free incubation layer stacked sequentially from the light-facing side to the back-facing side.
[0030] Each layer of the N-type microcrystalline stack is formed by depositing a film by progressively increasing the ratio of N-type doped gas to silane.
[0031] The refractive index of the first conductive film layer is 1.75-1.9, and the refractive index of the N-type semiconductor film layer is 2.5-2.9.
[0032] Example 1:
[0033] like Figure 1As shown, a heterojunction solar cell includes, in sequence from the light-facing side to the back-facing side, a first electrode 7N, a first conductive film layer 6N, an N-type semiconductor film layer 5, an intrinsic film layer 4, a semiconductor substrate 1, a tunneling oxide layer 2, a P-type carbon-doped semiconductor film layer, a high-concentration P-type doped semiconductor film layer, a second conductive film layer 6P, and a second electrode 7P. The first conductive film layer 6N completely covers the N-type semiconductor film layer, and the first electrode 7N is electrically connected to the N-type semiconductor film layer 5 through the first conductive film layer 6N. The second conductive film layer 6P completely covers the high-concentration P-type doped semiconductor film layer, and the second electrode 7P is electrically connected to the high-concentration P-type doped semiconductor film layer through the second conductive film layer 6P. The P-type carbon-doped semiconductor film layer and the high-concentration P-type doped semiconductor film layer together constitute the P-type semiconductor film layer 3.
[0034] The semiconductor substrate 1 is an N-type single-crystal silicon wafer, and the light-facing surface of the semiconductor substrate 1 is provided with a pyramidal textured surface, the size of which is 5µm.
[0035] The intrinsic film layer 4 is an intrinsic amorphous silicon layer with a thickness of 6 nm; the N-type semiconductor film layer 5 has a thickness of 13 nm.
[0036] The P-type carbon-doped semiconductor film is a P-type carbon-doped polycrystalline silicon layer 3A, and the high-concentration P-type doped semiconductor film is a high-concentration P-type doped polycrystalline silicon layer 3B.
[0037] The thickness of the tunneling oxide layer 2 is 2 nm; the thickness of the P-type carbon-doped polycrystalline silicon layer 3A is 60 nm, and the sheet resistance is 100 Ω / □; the thickness of the high-concentration P-type doped polycrystalline silicon layer 3B is 100 nm, and the sheet resistance is 50 Ω / □.
[0038] The first conductive film layer 6N and the second conductive film layer 6P are transparent conductive film layers.
[0039] The transparent conductive film is a gallium-doped and zinc-doped indium oxide film.
[0040] The thickness of the first conductive film layer 6N is 60 nm; the thickness of the second conductive film layer 6P is 55 nm.
[0041] The N-type semiconductor film layer 5 is an N-type microcrystalline stack; the N-type microcrystalline stack includes an oxygen-free microcrystalline layer 5C, an oxygen-containing microcrystalline layer 5B, and an oxygen-free incubation layer 5A, which are sequentially stacked from the light-facing side to the back-facing side. Each film layer of the N-type microcrystalline stack is formed by depositing and increasing the ratio of N-type dopant gas to silane in stages.
[0042] The first conductive film layer 6N has a refractive index of 1.8, and the N-type semiconductor film layer 5 has a refractive index of 2.6.
[0043] Example 2:
[0044] The only difference between this embodiment and Embodiment 1 is that: Figure 2 As shown, the N-type semiconductor film is an N-type microcrystalline silicon layer 5D, which is a single film layer without oxygen doping.
[0045] Example 3:
[0046] The only difference between this embodiment and Embodiment 1 is that: Figure 3 As shown, the P-type carbon-doped semiconductor film is a P-type carbon-doped microcrystalline silicon layer 3C, and the high-concentration P-type doped semiconductor film is a high-concentration P-type doped microcrystalline silicon layer 3D.
[0047] Example 4:
[0048] The only difference between this embodiment and Embodiment 1 is that: Figure 4 As shown, the semiconductor substrate 1 does not have a pyramidal textured surface on its light-facing side.
[0049] Comparative Example 1:
[0050] The only difference between this comparative example and Example 1 is that: Figure 5 As shown, the P-type semiconductor film is a P-type polycrystalline silicon layer 3E.
[0051] Comparative Example 2:
[0052] The only difference between this comparative example and Example 2 is that the refractive index of the first conductive film layer is 1.95, and the refractive index of the N-type semiconductor film layer is 3.3.
[0053] Isc / KA Voc / V FF Eta Example 1 1 1 1 1 Example 2 0.92 1 1 0.92 Example 3 1.01 1 0.97 0.9797 Example 4 0.85 1 0.95 0.8075 Comparative Example 1 0.97 1 0.98 0.9506 Comparative Example 2 0.90 1 0.98 0.9016
[0054] The table above shows the performance test results of the solar cells prepared in each embodiment and comparative example. As can be seen from the table, the short-circuit current Isc, open-circuit voltage Voc, fill factor FF, and conversion efficiency Eta of the solar cells prepared in the embodiments of the present invention are all at relatively high levels.
[0055] In the above embodiments of the present invention, the front window layer adopts an N-type oxygen-doped microcrystalline silicon layer scheme, which has a wider optical bandgap and less optical loss. Furthermore, compared with the front light-facing layer, the heterojunction microcrystalline scheme of the same thickness exhibits superior response to PVD sputtering, maintaining a higher passivation level and final conversion efficiency.
[0056] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.
Claims
1. A heterojunction solar cell, characterized in that: It includes a first electrode, a first conductive film layer, an N-type semiconductor film layer, an intrinsic film layer, a semiconductor substrate, a tunneling oxide layer, a P-type carbon-doped semiconductor film layer, a high-concentration P-type doped semiconductor film layer, a second conductive film layer, and a second electrode, which are sequentially stacked from the light-facing side to the back-facing side. The P-type carbon-doped semiconductor film layer is a P-type carbon-doped polycrystalline silicon layer, and the high-concentration P-type doped semiconductor film layer is a high-concentration P-type doped polycrystalline silicon layer. The first conductive film layer completely covers the N-type semiconductor film layer, and the first electrode is electrically connected to the N-type semiconductor film layer through the first conductive film layer. The second conductive film layer completely covers the high-concentration P-type doped semiconductor film layer, and the second electrode is electrically connected to the high-concentration P-type doped semiconductor film layer through the second conductive film layer.
2. The heterojunction solar cell according to claim 1, characterized in that: The semiconductor substrate is a single-crystal silicon wafer, and the light-facing surface of the semiconductor substrate is provided with a pyramidal textured surface, the size of which is 1-10 μm.
3. The heterojunction solar cell according to claim 1, characterized in that: The intrinsic film layer is an intrinsic amorphous silicon layer with a thickness of 3-12 nm; the N-type semiconductor film layer has a thickness of 9-20 nm.
4. The heterojunction solar cell according to claim 1, characterized in that: The thickness of the tunneling oxide layer is 1-3 nm; the total thickness of the P-type carbon-doped polycrystalline silicon layer and the high-concentration P-type doped polycrystalline silicon layer is 100-250 nm, and the sheet resistance is 30-150 Ω / □.
5. The heterojunction solar cell according to claim 1, characterized in that: The first conductive film layer and / or the second conductive film layer are transparent conductive film layers or composite stacks of transparent conductive film layers and metal film layers.
6. The heterojunction solar cell according to claim 5, characterized in that: The thickness of the first conductive film layer is 50-70 nm; the thickness of the second conductive film layer is 30-150 nm.
7. The heterojunction solar cell according to any one of claims 1-6, characterized in that: The N-type semiconductor film is an N-type microcrystalline stack; the N-type microcrystalline stack comprises one or more oxygen-containing microcrystalline layers and one or more oxygen-free microcrystalline layers.
8. The heterojunction solar cell according to claim 7, characterized in that: The N-type microcrystalline stack includes an oxygen-free microcrystalline layer, an oxygen-containing microcrystalline layer, and an oxygen-free incubation layer stacked sequentially from the light-facing side to the back-facing side.
9. The heterojunction solar cell according to claim 7, characterized in that: Each layer of the N-type microcrystalline stack is formed by depositing a film by progressively increasing the ratio of N-type doped gas to silane.
10. The heterojunction solar cell according to claim 7, characterized in that: The refractive index of the first conductive film layer is 1.75-1.9, and the refractive index of the N-type semiconductor film layer is 2.5-2.9.