Solar cell

Abstract

The utility model provides a solar cell, a silicon substrate of the solar cell is a P-type silicon substrate, a heavily doped layer, a superlattice structure layer and a first dielectric layer are sequentially stacked on a first surface of the silicon substrate, and a second dielectric layer is arranged on a second surface of the silicon substrate. According to the solar cell, heavy doping is carried out on the surface of the silicon substrate, and one side of the first surface and one side of the second surface of the silicon substrate adopt passivation contact structures, namely the first dielectric layer and the second dielectric layer, so that the passivation effect of the solar cell is improved, the loss of the solar cell during photoelectric conversion is reduced, and the photoelectric conversion efficiency of the solar cell is improved. And the photoelectric conversion efficiency of the solar cell is improved. And the additionally arranged superlattice structure layer can expand the wavelength absorption range of the solar cell on the solar spectrum, thereby being beneficial to improving the light utilization rate and further improving the photoelectric conversion efficiency of the solar cell.

Description

Technical Field

[0001] The utility model relates to the technical field of solar energy photoelectricity, in particular to a solar cell. Background Art

[0002] The mainstream solar cells on the market are mainly passivated contact cells with N-type crystalline silicon as the carrier. Its structure is that the film layers on the back of the N-type crystalline silicon are sequentially formed from the outside to the outside, including a dielectric layer and a phosphorus-doped polysilicon layer. The two together form a passivated contact structure, providing a good interface passivation effect for the back of the silicon wafer.

[0003] However, in the above method, the front side of the passivated contact cell uses the traditional boron diffusion method to form a PN junction, and the PN junction formed by boron and silicon has a narrow band gap, which results in the inability to effectively utilize the short-wave ultraviolet light on the front side, and the light utilization rate is low, which in turn leads to a decrease in the photoelectric conversion efficiency of the passivated contact cell. Utility Model Content

[0004] The utility model discloses a solar cell to improve the utilization rate of photons and enhance the photoelectric conversion efficiency of the solar cell.

[0005] In order to achieve the above object, the utility model discloses a solar cell, comprising:

[0006] A silicon substrate, wherein the silicon substrate is a P-type silicon substrate, and the silicon substrate comprises a first surface and a second surface opposite to each other;

[0007] A heavily doped layer, a superlattice structure layer and a first dielectric layer are sequentially stacked on the first surface;

[0008] A second dielectric layer is disposed on the second surface.

[0009] As an optional implementation, the heavily doped layer is a heavily boron doped layer, and the doping concentration of boron in the heavily boron doped layer is 1.0E 20 cm -3 -2.0E 20 cm -3 , the doping depth is 0.2um-0.5um.

[0010] As an optional implementation manner, the superlattice structure in the superlattice structure layer is a boron-doped nano-silicon oxide superlattice structure.

[0011] As an optional implementation, the thickness of the superlattice structure layer is 2nm-3nm.

[0012] As an optional implementation, the thickness of the first dielectric layer is 3nm-4nm, and the thickness of the second dielectric layer is 1nm-2nm.

[0013] As an optional implementation, a boron-doped polysilicon layer is provided on a side of the first dielectric layer facing away from the superlattice structure layer, and a phosphorus-doped polysilicon layer is provided on a side of the second dielectric layer facing away from the silicon substrate.

[0014] As an optional implementation, the thickness of the boron-doped polysilicon layer is 250nm-300nm, and the thickness of the phosphorus-doped polysilicon layer is 150nm-200nm.

[0015] As an optional implementation manner, a first protective layer is provided on a side of the boron-doped polysilicon layer away from the first dielectric layer, and a second protective layer is provided on a side of the phosphorus-doped polysilicon layer away from the first dielectric layer.

[0016] As an optional implementation manner, a first metal electrode is provided on a side of the first protective layer away from the boron-doped polysilicon layer, and a second metal electrode is provided on a side of the second protective layer away from the phosphorus-doped polysilicon layer.

[0017] As an optional implementation, the first metal electrode extends from the first protection layer to the boron-doped polysilicon layer, and the second metal electrode extends from the second protection layer to the phosphorus-doped polysilicon layer.

[0018] Compared with the prior art, the beneficial effects of the utility model are:

[0019] A solar cell in the utility model uses P-type silicon as a silicon substrate, and a heavily doped layer, a superlattice structure layer and a first dielectric layer are stacked in sequence on the first surface of the P-type silicon substrate. By adding a heavily doped layer and a first dielectric layer on the first surface of the P-type silicon substrate, the holes in the solar cell can be better transmitted from the second surface to the first surface, and the electrons are prevented from moving from the second surface to the first surface, forming an electric field passivation effect, which is beneficial to improving the stability and photoelectric conversion efficiency of the solar cell. The superlattice structure layer added between the heavily doped layer and the first dielectric layer can expand the absorption of the solar cell to the long wavelength range of the solar spectrum, that is, it can absorb the positive short-wave ultraviolet light, thereby improving the light utilization rate and effectively improving the photoelectric conversion efficiency of the solar cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. 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 creative work.

[0021] Figure 1 It is a schematic diagram of the structure of the solar cell in the utility model;

[0022] Figure 2 It is a front view of the solar cell in the utility model.

[0023] Description of reference numerals:

[0024] 1. Solar cell; 11. Silicon substrate; 11a. First surface; 11b. Second surface; 12. Heavily doped layer; 13. Superlattice structure layer; 14a. First dielectric layer; 14b. Second dielectric layer; 15a. Boron-doped polysilicon layer; 15b. Phosphorus-doped polysilicon layer; 16a. First protective layer; 161. Aluminum oxide layer; 162. Silicon nitride layer; 16b. Second protective layer; 21. First metal electrode; 22. Second metal electrode. DETAILED DESCRIPTION

[0025] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0026] In the present invention, the terms "inside", "outside" and the like indicate positions or location relationships based on the positions or location relationships shown in the accompanying drawings. These terms are mainly used to better describe the present invention and its embodiments, and are not used to limit the indicated devices, elements or components to have a specific orientation, or to be constructed and operated in a specific orientation.

[0027] In addition, some of the above terms may be used to express other meanings in addition to indicating orientation or positional relationship. For example, the term "on" may also be used to express a certain dependency or connection relationship in some cases. For those skilled in the art, the specific meanings of these terms in this utility model can be understood according to specific circumstances.

[0028] In addition, the terms "disposed" and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral structure; it can be a mechanical connection, or an electrical connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be an internal connection between two devices, elements or components. For ordinary technicians in this field, the specific meanings of the above terms in this utility model can be understood according to specific circumstances.

[0029] In addition, the terms "first", "second", etc. are mainly used to distinguish different devices, elements or components (the specific types and structures may be the same or different), and are not used to indicate or imply the relative importance and quantity of the indicated devices, elements or components. Unless otherwise specified, "plurality" means two or more.

[0030] In the relevant technology, the mainstream solar cells on the market are mainly passivated contact cells with N-type crystalline silicon as the carrier. Its structure is that the film layers on the back of the N-type crystalline silicon are sequentially formed from the outside to the outside, including a dielectric layer and a phosphorus-doped polysilicon layer. The two together form a passivated contact structure, providing a good interface passivation effect for the back of the silicon wafer.

[0031] However, in the above method, the front side (facing the light side) of the passivated contact cell uses the traditional boron diffusion method to form a PN junction. When preparing the passivated contact cell, it is necessary to use high temperature to push the boron atoms into the silicon wafer. Among them, the temperature range of boron diffusion is 980℃-1050℃. In this method, firstly, the process temperature required for this preparation method is relatively high, which puts a heavy burden on the production machine and causes a large loss of electric energy. Secondly, when the PN junction is formed by the traditional method, a large number of electrons will be introduced into the band gap near the direct contact area between the front metal electrode and the PN junction, resulting in a large carrier recombination loss of the passivated contact cell, which in turn leads to a decrease in the photoelectric conversion efficiency of the passivated contact cell. Furthermore, the PN junction band gap formed by silicon and boron is narrow, and the short-wave ultraviolet light projected from the front cannot be effectively utilized, resulting in a low light utilization rate. In addition, the passivated contact cell uses N-type crystalline silicon as the silicon substrate, while most of the existing solar cell industry is still dominated by P-type crystalline silicon production equipment, so it is impossible to effectively transform and upgrade the existing industrial chain.

[0032] Based on this, the utility model provides a solar cell, which uses a P-type silicon wafer as a silicon substrate, and heavily dopes the surface of the silicon substrate, and the front and back sides of the solar cell both use a tunnel passivation basic structure, and use a PIN junction to replace the traditional PN junction to improve the passivation effect. Furthermore, a superlattice structure layer is added inside the solar cell to expand the absorption of the wavelength range of the solar spectrum, thereby improving the utilization rate of sunlight, which is conducive to improving the photoelectric conversion efficiency.

[0033] The technical solution of the utility model will be further described below in conjunction with embodiments and drawings.

[0034] See also Figure 1 The utility model provides a solar cell 1, wherein the silicon substrate 11 of the solar cell 1 is a P-type silicon substrate 11, a heavily doped layer 12, a superlattice structure layer 13 and a first dielectric layer 14a are sequentially stacked on a first surface 11a of the silicon substrate 11, and a second dielectric layer 14b is arranged on a second surface 11b.

[0035] The solar cell 1 of the utility model uses a P-type silicon wafer as the silicon substrate 11, which is compatible with the existing PERC (Passivated Emitter and Rear Cell, emitter and rear passivation) cell production line and has high mass production capability. The first surface 11a of the silicon substrate 11 is heavily doped, and the first surface 11a and the second surface 11b of the silicon substrate 11 both adopt a passivation contact structure, that is, the first dielectric layer 14a and the second dielectric layer 14b are respectively provided on the first surface 11a and the second surface 11b, which is conducive to improving the passivation effect of the solar cell 1, thereby reducing the loss of the solar cell 1 during the photoelectric conversion, and improving the photoelectric conversion efficiency of the solar cell 1. The superlattice structure layer 13 added between the heavily doped layer 12 and the first dielectric layer 14a can expand the wavelength absorption range of the solar cell 1 to the solar spectrum, which is conducive to improving the light utilization rate, thereby improving the photoelectric conversion efficiency of the solar cell 1.

[0036] It should be noted that the first surface 11a of the solar cell 1 is the light-facing surface of the solar cell 1 when it is working, and is used to receive sunlight, and the opposite surface is the second surface 11b which is the back of the solar cell 1. In addition, the silicon substrate 11 can be a P-type silicon substrate.

[0037] In some embodiments, the heavily doped layer 12 in the solar cell 1 may be a heavily boron doped layer, and the silicon substrate 11 is doped with boron at a high concentration and shallow junction depth, that is, the first surface 11a of the silicon substrate 11 is doped with boron at a higher concentration, and the diffusion depth of the boron doping from the first surface 11a of the silicon substrate toward the second surface 11b is shallow.

[0038] Optionally, the boron doping concentration is 1.0E 20 cm -3 -2.0E 20 cm -3 , specifically 1.0E 20 cm -3 , 1.5E 20 cm -3 and 2.0E 20 cm -3 The doping depth of boron is 0.2um-0.5um, specifically 0.2um, 0.3um, 0.4um and 0.5um, etc.

[0039] Exemplarily, before the heavily doped layer 12 is formed on the first surface 11a of the silicon substrate 11, the holes and electrons inside the silicon substrate 11 move irregularly. After the first surface 11a of the silicon substrate 11 is doped with heavy boron at a high concentration shallow junction depth, a built-in electric field is formed inside the silicon substrate 11, and holes can be transmitted from the inside of the silicon substrate 11 toward one side of the first surface 11a under the influence of the built-in electric field, while electrons move from the first surface 11a toward the inside of the silicon substrate, forming a passivation effect of the built-in electric field of the silicon substrate 11, thereby improving the stability and photoelectric conversion efficiency of the solar cell 1.

[0040] In some embodiments, the superlattice structure in the superlattice structure layer 13 is a boron-doped nano-silicon oxide superlattice structure. The superlattice structure layer 13 utilizes the band gap adjustability of nano-silicon oxide and the good barrier properties of boron atoms to form a superlattice quantum well in the superlattice structure layer 13. The superlattice quantum well has a quantum drive effect, which is beneficial to improving the transmission efficiency of electrons in the battery, thereby improving the photoelectric conversion efficiency.

[0041] Exemplarily, the superlattice structure layer 13 is a boron-doped silicon oxide superlattice structure layer 13 prepared by reacting SiH4, O2, and BCl3 on the first surface 11a. The superlattice structure layer 13 is a single-crystalline wide-bandgap material layer.

[0042] In some embodiments, the thickness of the superlattice structure layer 13 is 2nm-3nm, specifically 2nm, 2.5nm and 3nm. The superlattice structure layer 13 performs alternating boron doping on the lattice structure to form a new type of artificial periodic superdimensional lattice charging distribution, so that the original lattice band gap is widened, and high-energy short-wave light, such as ultraviolet light with the shortest wavelength, can be better absorbed. Therefore, it is beneficial to improve the utilization rate of light by the solar cell 1, and it is beneficial for photons to be better absorbed from the first surface 11a toward the second surface 11b.

[0043] In some embodiments, the thickness of the first dielectric layer 14a may be 3nm-4nm, specifically 3nm, 3.5nm, 4nm, etc. The thickness of the second dielectric layer 14b may be 1nm-2nm, specifically 1nm, 1.5nm, 2nm, etc.

[0044] Specifically, by designing the first dielectric layer 14a and the second dielectric layer 14b as above, the first surface 11a and the second surface 11b of the silicon substrate 11 can be passivated, and the first dielectric layer 14a and the second dielectric layer 14b can have a pinhole channel effect, so that the holes in the solar cell 1 can move in a directional manner, resulting in selective passage of carriers, which is beneficial to reduce the recombination loss of carriers and improve the photoelectric conversion efficiency.

[0045] See also Figure 2 In some embodiments, a boron-doped polysilicon layer 15a is provided on the side of the first dielectric layer 14a facing away from the superlattice structure layer 13, and a phosphorus-doped polysilicon layer 15b is provided on the side of the second dielectric layer 14b facing away from the silicon substrate 11. It can be understood that a boron-doped polysilicon layer 15a is added to the first surface 11a to form a PIN junction inside the solar cell 1. The PIN junction shunts the carriers in the solar cell 1, reduces the loss of the carriers and the metal electrode recombination, and improves the photoelectric conversion efficiency of the solar cell 1.

[0046] It should be noted that Figure 1 and Figure 2 It is only used to illustrate the structure of the solar cell 1 and does not represent the actual size of the solar cell 1 .

[0047] In some embodiments, the thickness of the boron-doped polysilicon layer 15a may be 250nm-300nm, specifically 250nm, 275nm, and 300nm. The thickness of the phosphorus-doped polysilicon layer 15b may be 150nm-200nm, specifically 150nm, 175nm, and 200nm. In specific settings, boron doping is required when the boron-doped polysilicon layer 15a is formed, and phosphorus doping is required when the phosphorus-doped polysilicon layer 15b is formed. Since the temperature required for doping is relatively high, in order to prevent boron from breaking through the first dielectric layer 14a located on the other side of the boron-doped polysilicon layer 15a, or to prevent phosphorus from breaking through the second dielectric layer 14b located on the other side of the phosphorus-doped polysilicon layer 15b, the thickness of the boron-doped polysilicon layer 15a and the phosphorus-doped polysilicon layer 15b may be appropriately increased.

[0048] In some embodiments, a first protective layer 16a is provided on the side of the boron-doped polysilicon layer 15a facing away from the first dielectric layer 14a, and a second protective layer 16b is provided on the side of the phosphorus-doped polysilicon layer 15b facing away from the first dielectric layer 14a. Specifically, by providing the above protective layer on the surface of the solar cell 1, it is beneficial to increase the passivation effect of the solar cell 1 and reduce the decrease in photon utilization rate caused by the influence of recombination.

[0049] Furthermore, the first protective layer 16a is located on one side of the first surface 11a and is directly exposed to sunlight. The first protective layer 16a can also reduce the reflection of sunlight by the solar cell 1, which is beneficial for the solar cell 1 to better absorb sunlight, improve the utilization rate of sunlight, and help improve the photoelectric conversion efficiency of the solar cell 1.

[0050] Optionally, the first protective layer 16a and the second protective layer 16b may be, but are not limited to, coatings of materials such as aluminum oxide and silicon nitride. The above is only used as an example to facilitate understanding of the solution of the utility model, and the utility model is not limited here.

[0051] Specifically, the first protective layer 16a includes an aluminum oxide layer 161 and a silicon nitride layer 162 sequentially arranged on the side of the boron-doped polysilicon layer 15a away from the first dielectric layer 14a, and the second protective layer 16b is a silicon nitride layer 162. Exemplarily, the silicon nitride layer 162 is located at the outermost side of the solar cell 1, which improves the solar light absorption efficiency and hydrogen ion passivation of the solar cell 1, and protects the aluminum oxide passivation layer to prevent collapse after sintering and passivation failure. Compared with the second surface 11b, the first surface 11a is the light-facing surface, and the recombination of the light-facing surface should be reduced to increase the photon utilization rate. Therefore, compared with the second protective layer 16b, the first protective layer 16a is additionally provided with an aluminum oxide layer 161, which further improves the passivation effect of the first protective layer 16a on the solar cell 1.

[0052] In some embodiments, a first metal electrode 21 is provided on a side of the first protective layer 16a away from the boron-doped polysilicon layer 15a, and a second metal electrode 22 is provided on a side of the second protective layer 16b away from the phosphorus-doped polysilicon layer 15b. It can be understood that the first metal electrode 21 and the second metal electrode 22, as current output terminals of the solar cell 1, can transfer charges from the inside of the solar cell 1 to the external circuit, which helps to complete the conversion and output of electrical energy.

[0053] In some embodiments, the first metal electrode 21 extends from the first protective layer 16a to the boron-doped polysilicon layer 15a, and the second metal electrode 22 extends from the second protective layer 16b to the phosphorus-doped polysilicon layer 15b. The first metal electrode 21 and the second metal electrode 22 are connected to the boron-doped polysilicon layer 15a and the phosphorus-doped polysilicon layer 15b, respectively, so that the metal electrode and the polysilicon layer form a good ohmic contact, which is conducive to the effective transmission of current and maintaining the good performance of the solar cell 1.

[0054] For example, referring to Table 1, the solar cell 1 provided by the present invention and the traditional passivated contact cell were subjected to a comparative test, and 500 cells of each type were tested to obtain the average value. The conversion efficiency (Eta), open circuit voltage (Uoc) and short circuit current (Isc) are mainly referred to.

[0055] Table 1

[0056] quantity category Eta-Ave(%) Uoc-Ave(V) Isc-Ave(A) FF-Ave(%) Rs(Ω) Rsh(Ω) IRev2(A) 500 Control group 25.88 0.7239 13.902 84.99 0.00123 1690 0.026 500 Experimental Group 26.04 0.7255 13.954 84.93 0.00129 1708 0.021

[0057] For ease of understanding, it should be noted that FF in Table 1 is the fill factor, Rs is the series resistance, Rsh is the parallel resistance, and IRev2 is the reverse current.

[0058] The solar cell 1 of the present invention is used as the experimental group, and the traditional passivated contact cell is used as the control group. According to Table 1 above, compared with the traditional passivated contact cell in the control group, the open circuit voltage and short circuit current of the solar cell 1 provided by the present invention are improved, and then compared with the traditional passivated contact cell, the solar cell 1 of the present invention is improved in photoelectric conversion rate, and has higher energy conversion efficiency, that is, it has better photoelectric conversion effect under the same lighting conditions.

[0059] The following is a brief description of the method for preparing the solar cell of the present application.

[0060] S1. Performing texturing treatment on the silicon substrate.

[0061] S2. A heavily doped layer, a superlattice structure layer, a first dielectric layer and a boron-doped polysilicon layer are formed on the first surface of the textured silicon substrate.

[0062] Specifically, the above S2 includes the following specific processes:

[0063] S201. Set the pressure in the preparation furnace tube to 10000 mTorr and the temperature to 400°C. Pass 50000 sccm of N2 into the furnace tube within 10 seconds to pre-ventilate the furnace tube to maintain the furnace tube at normal pressure and make the furnace door easy to open.

[0064] S202. Then, place the quartz boat into the furnace tube within 120 seconds.

[0065] S203, raise the temperature in the furnace tube back to 400°C within 400s.

[0066] S204: Pump down the pressure in the furnace tube to the bottom pressure within 200 seconds.

[0067] S205: Raise the pressure in the furnace tube to 10,000 mTorr within 25 seconds to check whether there is any leakage in the furnace tube.

[0068] S206, continue for 70 seconds, and maintain the temperature in the furnace tube.

[0069] S207, introduce 8800 sccm of N2O into the furnace tube within 60 seconds, and adjust the pressure to 1580 mTorr so that the furnace tube is filled with the reaction gas.

[0070] S208, raising the temperature in the furnace tube to 430°C, and injecting 2500 sccm of SiH4, 10800 sccm of H2 and 1000 sccm of BCl3 into the furnace tube within 45 seconds to grow a heavily boron-doped layer on the first surface of the silicon substrate.

[0071] S209, cooling down after the growth is completed.

[0072] S210, exhaust gas in the furnace tube is discharged and heated to 430°C within 800s.

[0073] S211, maintaining the furnace tube power at 6200W at 400°C and a pressure of 1580mTorr, introducing 8800sccm of N2O and 800sccm of BCl3 into the furnace tube within 250s, growing a superdimensional lattice on the heavily boron doped layer to form a superlattice structure layer.

[0074] S212, exhaust gas in the furnace tube is discharged within 800s and the temperature in the furnace tube is raised to 430℃.

[0075] S213, maintaining the furnace tube power at 6200W at 400°C and a pressure of 1580mTorr, introducing 8800sccm of N2O into the furnace tube within 1800s, and growing the first dielectric layer on the superlattice structure layer.

[0076] S214, exhaust gas in the furnace tube is discharged within 800s and the temperature in the furnace tube is raised to 430℃.

[0077] S215, raising the pressure in the furnace tube to 2400 mTorr, adding 2500 sccm of SiH4 and 7900 sccm of H2 into the furnace tube within 45 seconds, so that the furnace tube is filled with reaction gas.

[0078] S216, maintaining the furnace tube at a power of 6200 W, injecting 2500 sccm of SiH4 and 7900 sccm of H2 into the furnace tube within 400 s to grow i-polysilicon on the first dielectric layer.

[0079] S217, raise the pressure in the furnace tube to 3100 mTorr, and inject 2500 sccm of SiH4, 10800 sccm of H2 and 233 sccm of BCl3 into the furnace tube within 45 seconds to fill the furnace tube with reaction gases.

[0080] S218, maintaining the furnace tube power at 7200W, injecting 2500sccm of SiH4, 10800sccm of H2 and 233sccm of BCl3 into the furnace tube within 145s, and continuing to grow d-polysilicon on the basis of i-polysilicon.

[0081] S219, maintain the pressure in the furnace tube at 3100 mTorr, and add 2500 sccm of SiH4, 10000 sccm of H2 and 525 sccm of BCl3 into the furnace tube within 45 seconds to fill the furnace tube with reaction gases.

[0082] S220, maintaining the furnace tube at a power of 7200 W, injecting 2500 sccm of SiH4, 10000 sccm of H2 and 525 sccm of BCl3 into the furnace tube within 300 s, and continuing to grow d-polysilicon on the basis of d-polysilicon.

[0083] S221. Maintain the pressure in the furnace tube at 3100 mTorr, and add 2500 sccm of SiH4, 11000 sccm of H2 and 656 sccm of BCl3 into the furnace tube within 45 seconds to fill the furnace tube with reaction gases.

[0084] S222, maintaining the furnace tube at a power of 7200 W, introducing 2500 sccm of SiH4, 11000 sccm of H2 and 656 sccm of BCl3 into the furnace tube within 600 s, and continuing to grow d-polysilicon on the basis of d-polysilicon to obtain a boron-doped polysilicon layer.

[0085] S223, exhaust gas in the furnace tube will be discharged within 30s.

[0086] S224: The pressure in the furnace tube drops to 1750 mTorr, and 1408 sccm of SiH4 and 6160 sccm of N2O are added into the furnace tube within 45 seconds to keep the furnace tube full of gas.

[0087] S225, maintaining the furnace tube at a power of 6400 W, injecting 1408 sccm of SiH4 and 6160 sccm of N2O into the furnace tube within 80 seconds, growing a mask on the silicon wafer prepared above to protect the back side of the silicon wafer from being corroded.

[0088] S226: The furnace tube temperature drops to 400°C and is maintained for 60 seconds, and the exhaust gas in the furnace tube is discharged.

[0089] S227. Fill the furnace tube with 30,000 sccm of N2 within 120 seconds and fill the furnace tube to normal pressure (10,000 mTorr).

[0090] S228, maintaining the above furnace tube state, and pulling the quartz boat out of the furnace tube.

[0091] S229, end and set the standby temperature to 400°C.

[0092] S3, performing edge expansion and removal on the second surface of the silicon substrate, and polishing the second surface.

[0093] S4. Oxidizing the polished surface of the second surface to form a thin second dielectric layer.

[0094] S5. Depositing a phosphorus-doped polysilicon layer on the second dielectric layer.

[0095] S6, annealing and crystallizing the solar cell after the above steps.

[0096] S7, cleaning the solar cell after the above steps by a wet chemical cleaning method to remove the glass layer on the first surface and the second surface.

[0097] S8, depositing aluminum oxide and silicon nitride on the boron-doped polysilicon layer of the solar cell after the above steps to form a first protective layer.

[0098] S9, depositing silicon nitride on the phosphorus-doped polysilicon layer of the solar cell after the above steps to form a second protective layer.

[0099] S10, printing and sintering the metal patterns of the first protective layer and the second protective layer of the solar cell after the above steps and sintering them to the boron-doped polysilicon layer and the phosphorus-doped polysilicon layer respectively to form a first metal electrode and a second metal electrode.

[0100] S11. Testing the printed and sintered cells.

[0101] It should be noted that the above-mentioned preparation method of the solar cell and the experimental method, experimental data and related conclusions provided in Table 1 are only used to understand and illustrate the technical solution of the solar cell 1 of the present utility model.

[0102] The solar cell disclosed in the embodiment of the utility model is introduced in detail above. The principle and implementation method of the utility model are described in this article using specific examples. The description of the above embodiments is only used to help understand the solar cell of the utility model and its core concept. At the same time, for those skilled in the art, according to the concept of the utility model, there will be changes in the specific implementation method and application scope. In summary, the content of this specification should not be understood as limiting the utility model.

Claims

1. A solar cell, characterized in that: include: A silicon substrate, wherein the silicon substrate is a P-type silicon substrate, and the silicon substrate comprises a first surface and a second surface opposite to each other; A heavily doped layer, a superlattice structure layer and a first dielectric layer are sequentially stacked on the first surface; A second dielectric layer is disposed on the second surface.

2. A solar cell according to claim 1, characterized in that: The thickness of the superlattice structure layer is 2nm-3nm.

3. A solar cell according to claim 1, characterized in that: The thickness of the first dielectric layer is 3nm-4nm, and the thickness of the second dielectric layer is 1nm-2nm.

4. A solar cell according to any one of claims 1 to 3, characterized in that: A boron-doped polysilicon layer is disposed on a side of the first dielectric layer away from the superlattice structure layer, and a phosphorus-doped polysilicon layer is disposed on a side of the second dielectric layer away from the silicon substrate.

5. A solar cell as claimed in claim 4, characterized in that: The thickness of the boron-doped polysilicon layer is 250nm-300nm, and the thickness of the phosphorus-doped polysilicon layer is 100nm-150nm.

6. A solar cell as claimed in claim 4, characterized in that: A first protective layer is disposed on a side of the boron-doped polysilicon layer away from the first dielectric layer, and a second protective layer is disposed on a side of the phosphorus-doped polysilicon layer away from the first dielectric layer.

7. A solar cell according to claim 6, characterized in that: A first metal electrode is disposed on a side of the first protection layer away from the boron-doped polysilicon layer, and a second metal electrode is disposed on a side of the second protection layer away from the phosphorus-doped polysilicon layer.

8. A solar cell as claimed in claim 7, characterized in that: The first metal electrode extends from the first protection layer to the boron-doped polysilicon layer, and the second metal electrode extends from the second protection layer to the phosphorus-doped polysilicon layer.

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