Dielectric layer, preparation method, solar cell, and photovoltaic module

Abstract

A dielectric layer, a preparation method, a solar cell, and a photovoltaic module. The dielectric layer is used for a solar cell and comprises an aluminum oxynitride layer containing hydrogen, and the nitrogen content of the dielectric layer is higher than 4 wt% and the hydrogen content thereof is higher than 4 wt%.

Description

Dielectric layer and preparation method, solar cell, and photovoltaic module

[0001] Related applications

[0002] This application claims priority to Chinese patent application number CN2023111688368, filed on September 12, 2023, entitled “Dielectric layer and preparation method, solar cell, photovoltaic module”, the entire text of which is hereby incorporated by reference. Technical Field

[0003] The present application relates to the field of photovoltaic technology, and in particular to a dielectric layer and a preparation method thereof, a solar cell, and a photovoltaic module. Background Art

[0004] In solar cells, photogenerated carriers migrate to the cell's interface, recombine, and are lost, preventing them from being collected by the electrodes. This reduces the cell's photoelectric conversion efficiency. Conventional solar cell technologies employ passivation structures to passivate the cell's surface and reduce the recombination of photogenerated carriers there. However, some passivation structures exhibit poor interface continuity and high interface defect densities, making it difficult to maintain passivation effectiveness. Furthermore, these passivation structures struggle to increase the refractive index, hindering further improvements in the cell's photoelectric conversion efficiency.

[0005] Summary of the Invention

[0006] According to various embodiments of the present application, a dielectric layer and a preparation method thereof, a solar cell, and a photovoltaic module are provided.

[0007] In a first aspect, the present application provides a dielectric layer for a solar cell, wherein the dielectric layer comprises an aluminum oxynitride layer containing hydrogen, wherein the nitrogen content of the dielectric layer is higher than 4 wt % and the hydrogen content is higher than 4 wt %.

[0008] In some embodiments, the dielectric layer includes an aluminum oxynitride layer.

[0009] In some embodiments, the dielectric layer includes a first dielectric layer and a second dielectric layer stacked together.

[0010] In some embodiments, the first dielectric layer is an aluminum oxynitride layer.

[0011] In some embodiments, the second dielectric layer includes any one of an aluminum oxide layer, a gallium oxide layer, a titanium dioxide layer, a zirconium dioxide layer, and a tantalum pentoxide layer.

[0012] In some embodiments, a growth substrate of the second dielectric layer is a P-type substrate or an N-type substrate, and the first dielectric layer is disposed on a surface of the second dielectric layer facing away from the P-type substrate or the N-type substrate.

[0013] In some embodiments, the second dielectric layer includes an aluminum oxide layer.

[0014] In some embodiments, the thickness of the second dielectric layer is less than or equal to the thickness of the first dielectric layer.

[0015] In some embodiments, the dielectric layer has a thickness of less than 30 nm.

[0016] In some embodiments, the refractive index of the dielectric layer ranges from about 1.65 to about 2.10.

[0017] In some embodiments, the roughness of the dielectric layer is in a range of about 0.15 nm to about 0.3 nm.

[0018] In some embodiments, the P-type substrate includes any one of a P-type silicon wafer, a P-type epitaxial growth doping layer, and a P-type diffusion layer.

[0019] In some embodiments, the N-type substrate includes an N-type silicon wafer.

[0020] In a second aspect, the present application provides a method for preparing a dielectric layer, wherein the dielectric layer is the dielectric layer as described in the first aspect, and the preparation method comprises the following steps:

[0021] Chemical adsorption: sequentially providing an aluminum source and an oxygen source for chemical adsorption on the surface of the P-type substrate or the N-type substrate to complete a growth cycle, and performing a growth cycle x times to deposit the dielectric layer, wherein a nitrogen source is also provided for at least 10 of the x growth cycles, so that the nitrogen content of the dielectric layer is higher than 4 wt% and the hydrogen content is higher than 4 wt%;

[0022] Standing: standing the dielectric layer in an inert atmosphere at a temperature of 520° C. to 600° C. for a time of 10 min to 40 min.

[0023] In some embodiments, the dielectric layer includes a first dielectric layer and a second dielectric layer, and the chemical adsorption step includes:

[0024] providing the aluminum source and the oxygen source in sequence, performing chemical adsorption on the surface of the P-type substrate or the N-type substrate to complete a growth cycle, and performing y cycles of growth to deposit the second dielectric layer, where y is greater than 0;

[0025] The aluminum source and the oxygen source are provided in sequence, chemical adsorption is performed on the surface of the second dielectric layer facing away from the P-type substrate or the N-type substrate to complete one growth, and the first dielectric layer is deposited for z cycles of growth, and a nitrogen source is provided for at least 10 of the z cycles of growth.

[0026] In some embodiments, the step of allowing to stand comprises: allowing the first dielectric layer and the second dielectric layer to stand in an inert atmosphere at a temperature of about 520° C. to 600° C. for a time of about 10 min to 40 min.

[0027] In some embodiments, y is less than or equal to z.

[0028] In some embodiments, in the step of depositing the second dielectric layer, a growth temperature is about 250° C. to 400° C.

[0029] In some embodiments, in the step of depositing the first dielectric layer, a growth temperature is about 250° C. to 400° C.

[0030] In some embodiments, the gas flow rates of the aluminum source, the oxygen source, and the nitrogen source are approximately 20 sccm to 100 sccm.

[0031] In some embodiments, the aluminum source is provided for about 8 seconds to 12 seconds, the oxygen source is provided for about 8 seconds to 12 seconds, and the nitrogen source is provided for about 15 seconds to 25 seconds.

[0032] In some embodiments, the aluminum source includes a mixture of one or more of Al(CH3)3, AlCl3, Al(CH3)2Cl, and (CH3)2(C2H5)N:AlH3.

[0033] In some embodiments, the oxygen source comprises a mixture of one or more of H2O, O2, O3, N2O, and CO2;

[0034] In some embodiments, the nitrogen source includes a mixture of one or more of N2O and NH3.

[0035] In a third aspect, the present application discloses a solar cell, comprising the dielectric layer as described in the first aspect, and further comprising a protective layer stacked on a surface of the dielectric layer away from the P-type substrate or the N-type substrate.

[0036] In some embodiments, the protective layer has a thickness greater than or equal to 50 nm.

[0037] In some embodiments, the sum of the thicknesses of the dielectric layer and the protective layer is approximately 75 nm to 85 nm.

[0038] In some embodiments, the equivalent refractive index of the dielectric layer and the protective layer is approximately 1.85 to 2.20.

[0039] In some embodiments, the material of the protective layer includes one or more of silicon nitride, silicon oxynitride, silicon oxide, and silicon carbide, and the hydrogen content of the protective layer is greater than or equal to 1 wt %.

[0040] In some embodiments, the solar cell includes any one of a back-passivated solar cell, a passivated contact solar cell, an N-type back-contact solar cell, and a P-type back-contact solar cell.

[0041] In some embodiments, the solar cell is a back-passivated solar cell, comprising:

[0042] A first P-type silicon wafer, wherein the first P-type silicon wafer has a first surface and a second surface disposed opposite to each other, and the first surface is a light incident surface;

[0043] An N-type diffusion layer, the N-type diffusion layer is provided on the first surface;

[0044] a first passivation layer, the first passivation layer being provided on a side of the N-type diffusion layer facing away from the first P-type silicon wafer;

[0045] a first protective layer, the first protective layer being disposed on a side of the first passivation layer facing away from the first P-type silicon wafer;

[0046] a dielectric layer, the dielectric layer being an aluminum oxynitride layer, and the dielectric layer being disposed on the second surface;

[0047] a second protective layer, the second protective layer being disposed on a side of the aluminum oxynitride layer facing away from the first P-type silicon wafer; and

[0048] The first electrode structure includes a first electrode and a second electrode, the first electrode is in ohmic contact with the first P-type silicon wafer, and the second electrode is in ohmic contact with the N-type diffusion layer.

[0049] In some embodiments, the solar cell is a back-passivated solar cell, comprising:

[0050] A first P-type silicon wafer, wherein the first P-type silicon wafer has a first surface and a second surface disposed opposite to each other, and the first surface is a light incident surface;

[0051] An N-type diffusion layer, the N-type diffusion layer is provided on the first surface;

[0052] a first passivation layer, the first passivation layer being provided on a side of the N-type diffusion layer facing away from the first P-type silicon wafer;

[0053] a first protective layer, the first protective layer being disposed on a side of the first passivation layer facing away from the first P-type silicon wafer;

[0054] a dielectric layer, the dielectric layer comprising an aluminum oxide layer and an aluminum oxynitride layer stacked in sequence; the aluminum oxide layer is disposed on the second surface;

[0055] a second protective layer, the second protective layer being disposed on a side of the aluminum oxynitride layer facing away from the first P-type silicon wafer; and

[0056] The first electrode structure includes a first electrode and a second electrode, the first electrode is in ohmic contact with the first P-type silicon wafer, and the second electrode is in ohmic contact with the N-type diffusion layer.

[0057] In some embodiments, the solar cell is a passivated contact solar cell, comprising:

[0058] a first N-type silicon wafer, wherein the first N-type silicon wafer has a third surface and a fourth surface opposite to the third surface, wherein the third surface is a light incident surface;

[0059] A P-type diffusion layer, the P-type diffusion layer is provided on the third surface;

[0060] a dielectric layer, the dielectric layer being an aluminum oxynitride layer, the aluminum oxynitride layer being disposed on a side of the P-type diffusion layer facing away from the first N-type silicon wafer;

[0061] a third protective layer, the third protective layer being disposed on a side of the aluminum oxynitride layer facing away from the first N-type silicon wafer;

[0062] a first tunneling oxide layer, wherein the first tunneling oxide layer is provided on the fourth surface;

[0063] a first doped polysilicon layer, the first doped polysilicon layer being disposed on a side of the first tunneling oxide layer facing away from the first N-type silicon wafer;

[0064] a first anti-reflection layer, the first anti-reflection layer being disposed on a side of the first doped polysilicon layer facing away from the first N-type silicon wafer; and

[0065] The second electrode structure includes a third electrode and a fourth electrode, the third electrode is in ohmic contact with the P-type diffusion layer, and the fourth electrode is in ohmic contact with the first doped polysilicon layer.

[0066] In some embodiments, the solar cell is a passivated contact solar cell, comprising:

[0067] a first N-type silicon wafer, wherein the first N-type silicon wafer has a third surface and a fourth surface opposite to the third surface, wherein the third surface is a light incident surface;

[0068] A P-type diffusion layer, the P-type diffusion layer is provided on the third surface;

[0069] a dielectric layer, the dielectric layer comprising an aluminum oxide layer and an aluminum oxynitride layer stacked in sequence; the aluminum oxide layer being disposed on a side of the P-type diffusion layer facing away from the first N-type silicon wafer;

[0070] a third protective layer, the third protective layer being disposed on a side of the aluminum oxynitride layer facing away from the first N-type silicon wafer;

[0071] a first tunneling oxide layer, wherein the first tunneling oxide layer is provided on the fourth surface;

[0072] a first doped polysilicon layer, the first doped polysilicon layer being disposed on a side of the first tunneling oxide layer facing away from the first N-type silicon wafer;

[0073] a first anti-reflection layer, the first anti-reflection layer being disposed on a side of the first doped polysilicon layer facing away from the first N-type silicon wafer; and

[0074] The second electrode structure includes a third electrode and a fourth electrode, the third electrode is in ohmic contact with the P-type diffusion layer, and the fourth electrode is in ohmic contact with the first doped polysilicon layer.

[0075] In some embodiments, the solar cell is an N-type back-contact solar cell, and the solar cell further comprises:

[0076] a second N-type silicon wafer, wherein the second N-type silicon wafer has a fifth surface and a sixth surface opposite to the fifth surface, wherein the fifth surface is a light incident surface;

[0077] a second passivation layer, the second passivation layer being provided on the fifth surface;

[0078] a fourth protective layer, the fourth protective layer being provided on a side of the second passivation layer facing away from the second N-type silicon wafer;

[0079] a second tunneling oxide layer, the second tunneling oxide layer comprising a first portion and a second portion, the first portion and the second portion being disposed on the sixth surface;

[0080] a second doped polysilicon layer, the second doped polysilicon layer comprising a P-type doped polysilicon layer and an N-type doped polysilicon layer, the P-type doped polysilicon layer being disposed on a side of the first portion facing away from the second N-type silicon wafer, and the N-type doped polysilicon layer being disposed on a side of the second portion facing away from the second N-type silicon wafer;

[0081] a dielectric layer, the dielectric layer being an aluminum oxynitride layer, the dielectric layer comprising a third portion, a fourth portion, and a fifth portion, the third portion being provided on a side of the P-type doped polysilicon layer facing away from the second N-type silicon wafer, the fourth portion being provided on the sixth side and between the P-type doped polysilicon layer and the N-type doped polysilicon layer, and the fifth portion being provided on a side of the N-type doped polysilicon layer facing away from the second N-type silicon wafer;

[0082] a fifth protective layer, the fifth protective layer being disposed on a side of the third portion, the fourth portion, and the fifth portion facing away from the second N-type silicon wafer; and

[0083] The third electrode structure includes a fifth electrode and a sixth electrode, wherein the fifth electrode is in ohmic contact with the P-type doped polysilicon layer, and the sixth electrode is in ohmic contact with the N-type doped polysilicon layer.

[0084] In some embodiments, the solar cell is an N-type back-contact solar cell, and the solar cell comprises:

[0085] a second N-type silicon wafer, wherein the second N-type silicon wafer has a fifth surface and a sixth surface opposite to the fifth surface, wherein the fifth surface is a light incident surface;

[0086] a second passivation layer, the second passivation layer being provided on the fifth surface;

[0087] a fourth protective layer, the fourth protective layer being provided on a side of the second passivation layer facing away from the second N-type silicon wafer;

[0088] a second tunneling oxide layer, the second tunneling oxide layer comprising a first portion and a second portion, the first portion and the second portion being disposed on the sixth surface;

[0089] a second doped polysilicon layer, the second doped polysilicon layer comprising a P-type doped polysilicon layer and an N-type doped polysilicon layer, the P-type doped polysilicon layer being disposed on a side of the first portion facing away from the second N-type silicon wafer, and the N-type doped polysilicon layer being disposed on a side of the second portion facing away from the second N-type silicon wafer;

[0090] a dielectric layer comprising a third portion, a fourth portion, and a fifth portion;

[0091] The third portion includes a first aluminum oxide layer and a first aluminum oxynitride layer stacked in sequence, wherein the first aluminum oxide layer is provided on a side of the P-type doped polysilicon layer facing away from the second N-type silicon wafer;

[0092] The fourth portion includes a second aluminum oxide layer and a second aluminum oxynitride layer stacked in sequence, wherein the second aluminum oxide layer is provided on the sixth surface and is located between the P-type doped polysilicon layer and the N-type doped polysilicon layer;

[0093] The fifth portion includes a third aluminum oxide layer and a third aluminum oxynitride layer stacked in sequence, wherein the third aluminum oxide layer is provided on a side of the N-type doped polysilicon layer facing away from the second N-type silicon wafer; and

[0094] a fifth protective layer, the fifth protective layer being disposed on a side of the first aluminum oxynitride layer, the second aluminum oxynitride layer, and the third aluminum oxynitride layer facing away from the second N-type silicon wafer; and

[0095] The third electrode structure includes a fifth electrode and a sixth electrode, wherein the fifth electrode is in ohmic contact with the P-type doped polysilicon layer, and the sixth electrode is in ohmic contact with the N-type doped polysilicon layer.

[0096] In some embodiments, the solar cell is a P-type back-contact solar cell, and the solar cell comprises:

[0097] a second P-type silicon wafer, wherein the second P-type silicon wafer has a seventh surface and an eighth surface opposite to the seventh surface, wherein the seventh surface is a light incident surface;

[0098] a third passivation layer, the third passivation layer being provided on the seventh surface;

[0099] a sixth protective layer, the sixth protective layer being provided on a side of the third passivation layer facing away from the second P-type silicon wafer;

[0100] a third tunneling oxide layer, the third tunneling oxide layer being provided on the eighth surface;

[0101] An N-type doped polysilicon layer, the N-type doped polysilicon layer being disposed on a side of the third tunneling oxide layer facing away from the second P-type silicon wafer;

[0102] a dielectric layer, the dielectric layer being an aluminum oxynitride layer, the dielectric layer comprising a sixth portion and a seventh portion, the sixth portion being disposed on the eighth surface, and the seventh portion being disposed on a surface of the N-type doped polysilicon layer facing away from the second P-type silicon wafer;

[0103] a seventh protective layer, the seventh protective layer being provided on a side of the sixth portion and the seventh portion facing away from the second N-type silicon wafer; and

[0104] A fourth electrode structure includes a seventh electrode and an eighth electrode, wherein the seventh electrode is in ohmic contact with the second P-type silicon wafer, and the eighth electrode is in ohmic contact with the N-type doped polysilicon layer.

[0105] In some embodiments, the solar cell is a P-type back-contact solar cell, and the solar cell comprises:

[0106] a second P-type silicon wafer, wherein the second P-type silicon wafer has a seventh surface and an eighth surface opposite to the seventh surface, wherein the seventh surface is a light incident surface;

[0107] a third passivation layer, the third passivation layer being provided on the seventh surface;

[0108] a sixth protective layer, the sixth protective layer being provided on a side of the third passivation layer facing away from the second P-type silicon wafer;

[0109] a third tunneling oxide layer, the third tunneling oxide layer being provided on the eighth surface;

[0110] An N-type doped polysilicon layer, the N-type doped polysilicon layer being disposed on a side of the third tunneling oxide layer facing away from the second P-type silicon wafer;

[0111] a dielectric layer, the dielectric layer comprising a sixth portion and a seventh portion;

[0112] The sixth portion includes a fourth aluminum oxide layer and a fourth aluminum oxynitride layer stacked in sequence, and the fourth aluminum oxide layer is provided on the eighth surface;

[0113] The seventh portion includes a fifth aluminum oxide layer and a fifth aluminum oxynitride layer stacked in sequence, wherein the fifth aluminum oxide layer is provided on a side of the N-type doped polysilicon layer facing away from the second P-type silicon wafer;

[0114] a seventh protective layer, the seventh protective layer being disposed on a side of the fourth aluminum oxynitride layer and the fifth aluminum oxynitride layer facing away from the second N-type silicon wafer; and

[0115] A fourth electrode structure includes a seventh electrode and an eighth electrode, wherein the seventh electrode is in ohmic contact with the second P-type silicon wafer, and the eighth electrode is in ohmic contact with the N-type doped polysilicon layer.

[0116] In a fourth aspect, an embodiment of the present application further provides a photovoltaic module, which includes the solar cell as described in the third aspect.

[0117] The details of one or more embodiments of the present application are set forth in the following drawings and description. Other features, objects, and advantages of the present application will become apparent from the description, drawings, and claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0118] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the conventional technology, the following briefly introduces the drawings required for use in the embodiments or the conventional technology descriptions. Obviously, the drawings described below are merely embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on the disclosed drawings without any creative work.

[0119] FIG1 is a schematic diagram of a method for preparing a dielectric layer disclosed in one embodiment of the present application;

[0120] FIG2 is a schematic structural diagram of a back-passivated solar cell disclosed in one embodiment of the present application;

[0121] FIG3 is a schematic structural diagram of another back-passivated solar cell disclosed in one embodiment of the present application;

[0122] FIG4 is a schematic structural diagram of a passivated contact solar cell disclosed in one embodiment of the present application;

[0123] FIG5 is a schematic structural diagram of another passivated contact solar cell disclosed in one embodiment of the present application;

[0124] FIG6 is a schematic structural diagram of an N-type back-contact solar cell disclosed in one embodiment of the present application;

[0125] FIG7 is a schematic structural diagram of another N-type back-contact solar cell disclosed in one embodiment of the present application;

[0126] FIG8 is a schematic structural diagram of a P-type back-contact solar cell disclosed in one embodiment of the present application;

[0127] FIG9 is a schematic structural diagram of another P-type back-contact solar cell disclosed in an embodiment of the present application.

[0128] Reference numerals: 100, back-side passivated solar cell; 11, first P-type silicon wafer; 12, N-type diffusion layer; 13, first passivation layer; 14, first protective layer; 15, dielectric layer; 151, aluminum oxide layer; 152, aluminum oxynitride layer; 16, second protective layer; 171, first electrode; 172, second electrode;

[0129] 200, passivated contact solar cell; 21, first N-type silicon wafer; 22, P-type diffusion layer; 23, dielectric layer; 231, aluminum oxide layer; 232, aluminum oxynitride layer; 24, third protective layer; 25, first tunneling oxide layer; 26, first doped polysilicon layer; 27, first anti-reflection layer; 281, third electrode; 282, fourth electrode;

[0130] 300, N-type back-contact solar cell; 31, second N-type silicon wafer; 32, second passivation layer; 33, fourth protective layer; 34, second tunneling oxide layer; 341, first portion; 342, second portion; 351, P-type doped polysilicon layer; 352, N-type doped polysilicon layer; 36, dielectric layer; 361, third portion; 3611, first aluminum oxide layer; 3612, first aluminum oxynitride layer; 362, fourth portion; 3621, second aluminum oxide layer; 3622, second aluminum oxynitride layer; 363, fifth portion; 3631, third aluminum oxide layer; 3632, third aluminum oxynitride layer; 37, fifth protective layer; 381, fifth electrode; 382, ​​sixth electrode;

[0131] 400. P-type back-contact solar cell; 41. Second P-type silicon wafer; 42. Third passivation layer; 43. Sixth protective layer; 44. Third tunneling oxide layer; 45. N-type doped polysilicon layer; 46. Dielectric layer; 461. Sixth portion; 4611. Fourth aluminum oxide layer; 4612. Fourth aluminum oxynitride layer; 462. Seventh portion; 4621. Fifth aluminum oxide layer; 4622. Fifth aluminum oxynitride layer; 47. Seventh protective layer; 481. Seventh electrode; 482. Eighth electrode. DETAILED DESCRIPTION

[0132] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0133] One requirement for achieving high efficiency of solar cells is to effectively suppress surface recombination losses. x 、SiN x The use of such passivation structures for solar cell back passivation can easily lead to an inversion layer, resulting in a significant reduction in short-circuit current density. In addition, the film interface continuity of the passivation structure in traditional technology is poor, and the interface defect density D it High (up to 10 11 eV -1 cm -2 ~10 12 eV -1 cm -2 ) It is difficult to ensure the passivation effect, and the above passivation structures are difficult to increase the refractive index, which is not conducive to further improving the photoelectric conversion efficiency of solar cells.

[0134] Based on this, in a first aspect, the present application provides a dielectric layer for a solar cell, wherein the dielectric layer comprises an aluminum oxynitride layer containing hydrogen, wherein the nitrogen content of the dielectric layer is higher than 4 wt% and the hydrogen content is higher than 4 wt%. The dielectric layer comprises an aluminum oxynitride layer having a high density of negative charges Q f (10 12 cm -2 ~10 13 cm -2 ), can eliminate the parasitic capacitance effect and thus reduce the generation of parasitic current, thereby reducing the loss of short-circuit current density. In addition, high-density negative charges can achieve field-effect passivation, reduce the concentration of carriers near the interface of the solar cell, and thus reduce the recombination of carriers. The aluminum oxynitride layer has good growth properties, can reduce interface roughness, improve interface continuity, and reduce the distribution of dangling bonds. By regulating the element content of the dielectric layer, the nitrogen content of the dielectric layer is higher than 4wt%, nitrogen and hydrogen are easy to bond, more hydrogen elements can be introduced, and the hydrogen content can be maintained above 4wt%, thereby providing sufficient hydrogen atoms to achieve chemical passivation, saturate the dangling bonds on the substrate surface, reduce defect recombination centers, and reduce interface defect density D it (Can be reduced to 10 10 eV -1 cm -2 ~10 11 eV -1 cm -2 The increase in nitrogen content and the larger nitrogen atomic radius can increase the density of the aluminum oxynitride layer, thereby increasing the refractive index, improving the anti-reflection effect of the incident light surface of the solar cell, and increasing the absorption of incident light.

[0135] When the nitrogen content in the dielectric layer is lower than 4wt%, the introduction of hydrogen elements is reduced, resulting in a hydrogen content of less than 4wt%. There are not enough hydrogen atoms entering the interface between the dielectric layer and the P-type substrate or the N-type substrate, which is not conducive to the passivation of dangling bonds and the reduction of defect density.

[0136] Exemplarily, the nitrogen content and the hydrogen content may be any value within the above range, including but not limited to: 4wt%, 5wt%, 6wt%, 7wt%, 8wt%, 9wt%, 10wt%, 11wt%, 12wt%, 13wt%, 14wt%, 15wt%, 16wt%, 17wt%, 18wt%, 19wt%, 20wt%, 30wt% and 40wt%, etc.

[0137] In some embodiments, the dielectric layer includes an aluminum oxynitride layer, for example, a single aluminum oxynitride layer, which contains a relatively high density of negative charges Q f (10 12 cm -2 ~10 13 cm-2 ), can reduce the loss of short-circuit current density, reduce the minority carrier concentration near the interface through field effect passivation, thereby improving the photoelectric conversion efficiency of solar cells. Aluminum oxynitride single layer has a high nitrogen content, a dense single layer structure, and an improved refractive index, making it better for surface anti-reflection.

[0138] In some embodiments, the aluminum oxynitride layer may be combined with other film layers having a high density of negative charges to reduce the loss of short-circuit current density and improve the passivation effect.

[0139] In some embodiments, the dielectric layer includes a first dielectric layer and a second dielectric layer stacked together, and the second dielectric layer includes any one of an aluminum oxide layer, a gallium oxide layer, a titanium dioxide layer, a zirconium dioxide layer, and a tantalum pentoxide layer. The negative charge density Q of the aluminum oxide layer, the gallium oxide layer, the titanium dioxide layer, the zirconium dioxide layer, and the tantalum pentoxide layer is f High, both around 10 12 cm -2 ~10 13 cm -2 within the range.

[0140] By reducing the roughness of the dielectric layer, the interface dangling bonds can be reduced, thereby improving the passivation effect and reducing surface defects. In some embodiments, the roughness range of the dielectric layer is about 0.15nm to 0.3nm. The roughness of the dielectric layer of the embodiment of the present application is relatively low, the film layer has good continuity, and there are few interface dangling bonds, which can reduce the surface defect density of the P-type substrate or the N-type substrate. Exemplarily, the roughness range of the dielectric layer can be any point value within the above range, including but not limited to: 0.15nm, 0.16nm, 0.17nm, 0.18nm, 0.19nm, 0.20nm, 0.21nm, 0.22nm, 0.23nm, 0.24nm, 0.25nm, 0.26nm, 0.27nm, 0.28nm, 0.29nm and 0.30nm, etc.

[0141] To reduce the roughness of the dielectric layer, a film with even lower roughness can be composited with the aluminum oxynitride layer. When composited with films of different materials, there may be a lattice mismatch between the film layers due to differences in lattice constants between the different materials. At the interface between the two film layers, the material with the smaller lattice constant may have some dangling bonds, causing interface defects.

[0142] In some embodiments, the first dielectric layer is an aluminum oxynitride layer, and the second dielectric layer is an aluminum oxide layer. The lattice constant difference between aluminum oxide and aluminum oxynitride is small, and the lattice deformation at the junction of the aluminum oxide layer and the aluminum oxynitride layer is small, which can reduce dangling bonds. The aluminum oxide layer has good surface growth and wettability on the P-type substrate or N-type substrate, so that the roughness of the contact surface between the composite dielectric layer and the P-type substrate or N-type substrate is lower, the interface dangling bonds are fewer, and the interface passivation effect is significantly improved. In addition, the aluminum oxide layer and the aluminum oxynitride layer can also play a good complementary role. Although the aluminum oxide layer has a lower interface roughness, the aluminum oxide layer has fewer hydrogen atoms and insufficient chemical passivation ability; the aluminum oxynitride layer has a large number of hydrogen atoms, and the hydrogen atoms can move to the dangling bonds for chemical passivation, saturating the few remaining dangling bonds. Therefore, the composite of the aluminum oxide layer and the aluminum oxynitride layer can synergistically enhance efficiency, significantly reduce dangling bonds at the interface, and significantly reduce the interface defect density.

[0143] Optionally, the aluminum oxynitride layer may be disposed on the surface of the P-type substrate or the N-type substrate, and the aluminum oxide layer may be disposed on the side of the aluminum oxynitride layer facing away from the P-type substrate or the N-type substrate. Alternatively, the aluminum oxide layer may be disposed on the surface of the P-type substrate or the N-type substrate, and the aluminum oxynitride layer may be disposed on the side of the aluminum oxide layer facing away from the P-type substrate or the N-type substrate. This application does not limit the stacking method of the aluminum oxynitride layer and the aluminum oxide layer.

[0144] In some embodiments, an aluminum oxide layer may be disposed on the surface of a P-type substrate or an N-type substrate, and an aluminum oxynitride layer may be disposed on the side of the aluminum oxide layer facing away from the P-type substrate or the N-type substrate. By stacking the aluminum oxide layer on the surface closest to the P-type substrate or the N-type substrate, the film layer with lower roughness directly contacts the P-type substrate or the N-type substrate, thereby achieving a better passivation effect.

[0145] Taking the P-type substrate as an example, the mutual correlation and interaction between the N-type substrate and the dielectric layer can also be deduced according to the P-type substrate. In solar cells, the dielectric layer is often arranged between the protective layer (silicon nitride layer, etc.) and the P-type substrate (generally a silicon wafer). In order to reduce the reflectivity of the incident light surface as much as possible, make better use of the interference effect of light, and maximize the absorption effect of the solar cell on the incident light, it is necessary to meet the refractive index of the dielectric layer between the refractive index of the protective layer and the P-type substrate. Among them, the refractive index of the silicon nitride layer is about 2.10, the refractive index of the P-type substrate is about 3.42, and the refractive index of the dielectric layer can be The closer the refractive index of the dielectric layer is to 2.68, the better. In the embodiment of the present application, the refractive index of the dielectric layer ranges from about 1.65 to 2.10.

[0146] Exemplarily, the refractive index of the dielectric layer may be any value within the above range, for example, 1.65, 1.68, 1.70, 1.72, 1.75, 1.77, 1.80, 1.83, 1.85, 1.87, 1.88, 1.89, 1.90, 1.91, 1.92, 1.93, 1.94, 1.95, 1.96, 1.96, 1.97, 1.98, 1.99, 2.00, 2.02, 2.04, 2.06, 2.08 and 2.10, etc.

[0147] Furthermore, in the solar cell, the dielectric layer and the protective layer (silicon nitride layer, etc.) are arranged between the P-type substrate (generally a silicon wafer) and the photovoltaic glass. To improve the absorption of incident light by the solar cell, the overall refractive index of the dielectric layer and the protective layer (silicon nitride layer, etc.) must also meet certain requirements. For example, the overall refractive index of the dielectric layer and the protective layer needs to be between the refractive index of the photovoltaic glass (about 1.49) and the refractive index of the silicon wafer (about 3.42). The overall refractive index of the dielectric layer and the protective layer can be When the refractive index of the dielectric layer is between 1.65 and 2.10, the deviation from the refractive index of 2.26 is significant, and a thinner thickness can be set to maximize the refractive index of the dielectric layer. In some embodiments, the total thickness of the dielectric layer is less than 30 nm. This thin thickness can increase the refractive index of the dielectric layer, thereby bringing the overall refractive index of the dielectric layer and protective layer closer to 2.26, which is beneficial for the solar cell to absorb incident light.

[0148] In some embodiments, the thickness of the aluminum oxide layer is less than or equal to the thickness of the aluminum oxynitride layer. Due to the high nitrogen content and high density in the aluminum oxynitride layer, the refractive index of the aluminum oxynitride is higher than that of the aluminum oxide layer. Therefore, in order to make the refractive index of the composite dielectric layer closer to the refractive index of 2.26, it is necessary to set an aluminum oxynitride layer that is thicker than the aluminum oxide layer. The reflectivity of the incident light is low, which is conducive to the absorption of the incident light, thereby improving the photoelectric conversion efficiency. In addition, hydrogen atoms can more easily enter the interface between the aluminum oxide layer and the P-type substrate, better achieving chemical passivation of the interface. When the thickness of the aluminum oxide layer is larger than the thickness of the aluminum oxynitride layer, the aluminum oxide layer with a lower refractive index is thicker, further reducing the refractive index of the composite dielectric layer, which may lead to an increase in the reflectivity of the light incident surface of the solar cell, which is not conducive to the absorption of the incident light facing the front, and reducing the photoelectric conversion efficiency. In addition, if the thickness of the aluminum oxide layer is too thick, it may be difficult for hydrogen atoms to enter the interface between the aluminum oxide layer and the P-type substrate, making it difficult to achieve chemical passivation of the interface.

[0149] In the second aspect, the present application provides a method for preparing a dielectric layer as in the first aspect, which can be prepared by ALD (Atomic Layer Deposition), PEALD (Plasma Enhanced Atomic Layer Deposition), or MOCVD (Metal-organic Chemical Vapor Deposition). Taking the ALD method or the PEALD method as an example, by introducing a precursor into the reactor to reach the surface of the deposition substrate, chemical adsorption will occur on its surface to achieve the deposition of the film layer. One growth completes one atomic layer deposition, and the dielectric layer can be deposited by cyclic growth multiple times.

[0150] Referring to Figure 1 , when the dielectric layer is a single layer of aluminum oxynitride, the preparation method includes the following steps: Chemical adsorption: providing an aluminum source and an oxygen source for chemical adsorption on the surface of a P-type substrate or an N-type substrate to complete a primary growth cycle, and performing a growth cycle x times to deposit the dielectric layer. A nitrogen source is also provided for at least 10 of the x growth cycles to ensure that the dielectric layer has a nitrogen content exceeding 4 wt% and a hydrogen content exceeding 4 wt%. Resting: Resting the dielectric layer in an inert atmosphere at a temperature of 520°C to 600°C for a time of 10 to 40 minutes.

[0151] In order to better control the content of nitrogen in the process of depositing the aluminum oxynitride layer, the present application does not provide a nitrogen source in each growth gas source, but selectively introduces a nitrogen source. That is, in some growth times, only an aluminum source and an oxygen source are introduced, while in some growth times, an aluminum source, an oxygen source and a nitrogen source are introduced. In order to ensure that the nitrogen content is higher than 4wt% and the hydrogen content is higher than 4wt%, in the total number of cycles x, it is ensured that an additional nitrogen source is provided for at least 10 times. That is, it can be understood that the total number of cycles x is greater than or equal to 10, and x can be 10, 15, 20, 22, 25, 27, 30, 32, 35, 40, 45, 50, 55, 60, 70, 80, 100, 120 and 150, etc.

[0152] In some embodiments, the aluminum source may include one or more of Al(CH3)3, AlCl3, Al(CH3)2Cl, and (CH3)2(C2H5)N:AlH3. The oxygen source may include one or more of H2O, O2, O3, N2O, and CO2. The nitrogen source may include one or more of N2O and NH3. The above-mentioned precursor substances have high volatility, thermal stability, reactivity, and safety, and can chemically react with each other under conditions such as heating or ionization. During the cyclic growth process, they can not only react with the surface groups generated in the previous growth, but also generate new reactive groups for the next precursor reaction.

[0153] Taking the ALD method as an example, the ALD method requires that the aluminum source, oxygen source, and nitrogen source can react with each other under heating conditions. Al(CH3)3, H2O, and NH3 can be selected. For example, the preparation process is as follows: H2O is first introduced into the reactor to adsorb -OH on the surface of the P-type substrate. Then, Al(CH3)3 is introduced. Al(CH3)3 undergoes saturated chemical adsorption with -OH, forming unsaturated aluminum-containing functional groups. Excess Al(CH3)3 and impurity gases are evacuated. H2O is then introduced to react with the unsaturated aluminum-containing functional groups, allowing oxygen to bond with aluminum to form new functional groups. Excess H2O and impurities are then evacuated. During growth cycles requiring the introduction of a nitrogen source, NH3 is introduced for chemical adsorption until the functional groups are saturated, ensuring that aluminum atoms are fully bonded to nitrogen atoms, which in turn bond to a large number of hydrogen atoms. Excess NH3, generated CH4, and other impurities are then evacuated.

[0154] In some embodiments, when the dielectric layer includes a second dielectric layer and a first dielectric layer stacked sequentially, the second dielectric layer is an aluminum oxide layer, and the first dielectric layer is an aluminum oxynitride layer, the preparation method includes the following steps:

[0155] An aluminum source and an oxygen source are sequentially provided, and chemical adsorption is performed on the surface of a P-type substrate or an N-type substrate to complete a growth cycle, and a second dielectric layer is deposited y times in a cycle, where y is greater than 0;

[0156] An aluminum source and an oxygen source are sequentially provided, and chemical adsorption is performed on the surface of the second dielectric layer facing away from the P-type substrate or the N-type substrate to complete a growth cycle. The first dielectric layer is deposited through a cycle z, and a nitrogen source is also provided during at least three of the z cycles. Specifically, it can be understood that to ensure that the nitrogen content is greater than 4 wt% and the hydrogen content is greater than 4 wt%, the nitrogen source is additionally provided during at least 10 of the total z cycles. Specifically, it can be understood that the total number of cycles x is greater than or equal to 10, and x can be 11, 15, 20, 22, 25, 27, 30, 32, 35, 40, 45, 50, 55, 60, 70, 80, 100, 120, and 150, etc.

[0157] The preparation method of the first dielectric layer and the second dielectric layer is introduced using the ALD method as an example. Similarly, in the deposition of the aluminum oxide layer, the ALD method also requires that the aluminum source and the oxygen source can react with each other under heating conditions. Therefore, Al(CH3)3 and H2O that can react with each other are selected.

[0158] For example, the preparation process is as follows: first, an aluminum oxide layer is deposited. H2O is introduced into the reactor to adsorb -OH groups on the surface of the P-type substrate or N-type substrate. Then, Al(CH3)3 is introduced. Al(CH3)3 undergoes saturated chemical adsorption with -OH groups on the surface of the P-type substrate or N-type substrate to generate unsaturated aluminum-containing functional groups. Excess Al(CH3)3 and impurity gases are evacuated. Then, H2O is introduced again for saturated chemical adsorption, so that oxygen atoms bond with aluminum atoms while also generating new -OH groups to provide bonding sites for deposition of an aluminum oxynitride layer. Excess H2O and impurities are evacuated to complete one growth cycle. The growth cycle is repeated y times to deposit the aluminum oxide layer. For example, y can be 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 20, 30, 40, 50, 60, 70, 80, 100, 150, etc.

[0159] Next, the aluminum oxynitride layer is deposited. Al(CH3)3 is first introduced into the reactor. Al(CH3)3 undergoes saturated chemical adsorption with the large amount of newly generated -OH on the surface of the aluminum oxide layer, generating unsaturated aluminum-containing functional groups, while evacuating excess Al(CH3)3 and impurity gases. H2O is then introduced to chemically adsorb the unsaturated functional groups until saturation occurs, allowing oxygen atoms to connect to aluminum atoms and evacuating excess H2O and impurities. During the growth times when a nitrogen source is required, NH3 is introduced for chemical adsorption until saturation occurs, generating -NH2 to replace -CH3 and connect to Al, or -NH2 to connect directly to Al and simultaneously connect to H, evacuating excess NH3 and impurities, thus completing one growth cycle.

[0160] In some embodiments, the deposition of a single aluminum oxynitride layer or a composite dielectric layer of an aluminum oxide layer and an aluminum oxynitride layer can also be performed using the PEALD method. Ionization assistance can be used to achieve lower reaction temperatures and lower energy consumption. Accordingly, the oxygen source can be replaced with O2. Compared to H2O, O2 has the following two advantages: First, the reaction conditions for O2 are less stringent. The PEALD method does not require the aluminum, oxygen, and nitrogen sources to react with each other; chemical adsorption of the three can be achieved through ionization. Second, O2 facilitates the maintenance of the reaction equipment. Although H2O is relatively stable, it is difficult to completely evacuate the H2O after adsorption. Residual H2O reacts with subsequent process gases to produce byproducts, which can cause corrosion and increase the amount of thin film deposited on reaction equipment such as quartz tubes. Once the film reaches a certain thickness, it will fall off, affecting the process and increasing the frequency and difficulty of maintenance of the reaction equipment. In contrast, O2 generates oxygen ions through ionization. Oxygen ions have a shorter lifespan and will deactivate within a certain period of time even if evacuation is not possible. This can reduce side reactions and reduce wear and tear on the reaction equipment.

[0161] Taking the P-type substrate as an example, the N-type substrate can be derived similarly to the P-type substrate. In some embodiments, after the dielectric layer is prepared, the dielectric layer needs to be allowed to stand in an inert atmosphere, with a standing temperature of about 520°C to 600°C and a standing time of about 10min to 40min. It can enable the hydrogen atoms in the dielectric monolayer to move to the interface between the P-type substrate and the aluminum oxynitride layer, or enable the hydrogen atoms in the composite dielectric layer to move to the interface between the P-type substrate and the aluminum oxide layer, or the aluminum oxide layer and the aluminum oxynitride layer, thereby chemically passivating the dangling bonds between the interfaces. When the standing temperature is relatively low, it may cause insufficient activity of hydrogen atoms and weak mobility. In addition, the standing step can also allow the residual methyl groups (CH3) in the composite dielectric layer to decompose from the dielectric layer, thereby further bonding the three atoms of aluminum, oxygen, and nitrogen, increasing the density of the dielectric layer to increase the refractive index. For example, the inert atmosphere can be nitrogen, helium, etc. The standing temperature may be any value within the above range, including but not limited to 520° C., 530° C., 540° C., 550° C., 560° C., 570° C., 580° C., 590° C., and 600° C. The standing time may be any value within the above range, including but not limited to 10 min, 15 min, 20 min, 25 min, 30 min, 35 min, and 40 min.

[0162] In some embodiments, to ensure that the composite dielectric layer has a higher refractive index and minimize the distance that hydrogen atoms in the aluminum oxynitride layer and the aluminum oxide layer need to migrate to the interface with the p-type substrate, the thickness of the aluminum oxide layer needs to be less than or equal to the thickness of the aluminum oxynitride layer. Because the thickness of a single growth is the thickness of a single atomic layer, the total number of growth cycles (y) for the aluminum oxide layer needs to be less than or equal to the total number of growth cycles (z) for the aluminum oxynitride layer.

[0163] In some embodiments, the primary growth temperature is approximately 250°C to 400°C. This can effectively maintain the activity of the precursor during the primary growth process, ensuring chemical adsorption and reaction, so that the dielectric layer can meet the growth thickness and density requirements. Furthermore, it can maintain the structural stability of the precursor during the primary growth process, preventing precursor decomposition or chemical bond breakage of chemically adsorbed precursors, which could cause the precursor to desorb from the P-type substrate, affecting the density of the dielectric layer and resulting in a thin dielectric layer. When the primary growth temperature is relatively low, the precursor may be insufficiently active and have low reaction activity. When the primary growth temperature is relatively high, the precursor may decompose, affecting adsorption and reaction.

[0164] Illustratively, the temperature of a single growth may be any value within the above range, including but not limited to 250°C, 260°C, 270°C, 280°C, 290°C, 300°C, 310°C, 320°C, 330°C, 340°C, 350°C, 360°C, 370°C, 380°C, 390°C and 400°C, etc.

[0165] In some embodiments, the gas flow rates of the aluminum source, oxygen source, and nitrogen source are approximately 20 sccm to 100 sccm. The aluminum source is provided for approximately 8 to 12 seconds, the oxygen source is provided for approximately 8 to 12 seconds, and the nitrogen source is provided for approximately 15 to 25 seconds. The different gas introduction times in each cycle are designed to ensure that the gas molecules can completely cover the silicon wafer surface. The flow rates and introduction times affect the number of newly generated reaction sites of the precursor, and controlling the time and flow rates can ensure that the precursor molecules can chemically adsorb to all surface reaction sites. The nitrogen source introduction time is controlled to 15 to 25 seconds. On the one hand, since the nitrogen source is introduced less frequently than the oxygen and aluminum sources, setting the nitrogen source introduction time longer than the oxygen and aluminum sources allows for sufficient chemical adsorption with less nitrogen source. This also increases the nitrogen content in the dielectric layer, thereby continuously introducing hydrogen and ensuring the nitrogen and hydrogen content. For example, the gas flow rate can be any value within the above range, including but not limited to 20 sccm, 30 sccm, 40 sccm, 50 sccm, 60 sccm, 70 sccm, 80 sccm, 90 sccm, and 100 sccm. The supply time of the aluminum source, oxygen source, and nitrogen source can be any value within the above range, for example, 8 s, 9 s, 10 s, 11 s, 12 s, etc. The supply time of the nitrogen source can be 15 s, 16 s, 17 s, 18 s, 19 s, 20 s, 21 s, 22 s, 23 s, 24 s, and 25 s, etc.

[0166] In some embodiments, after the aluminum source, oxygen source, and nitrogen source are introduced, evacuation is required to remove residual gases, thereby removing excess precursors and byproducts such as CH4, thereby reducing the impact on subsequent cyclic growth. The evacuation time can be 8s to 12s to ensure that excess gas molecules can be completely evacuated. Exemplarily, the evacuation time can be any value within the above range, including but not limited to 8s, 9s, 10s, 11s, and 12s.

[0167] In a third aspect, the present application provides a solar cell, comprising the dielectric layer as described in the first aspect, and further comprising a protective layer stacked on a surface of the dielectric layer away from the P-type substrate or the N-type substrate.

[0168] The material of the protective layer includes one or more combinations of silicon nitride, silicon oxynitride, silicon oxide, and silicon carbide. The temperature and time required for the deposition of the protective layer are close to the temperature and time required for the static state of the dielectric layer. Therefore, in the industrial production process, after the dielectric layer is deposited, the protective layer can be directly prepared. The temperature and time of the protective layer deposition are controlled so that the protective layer is deposited on the surface of the dielectric layer, and at the same time, the dielectric layer completes the static state.

[0169] The solar cell includes a P-type substrate or an N-type substrate, and the solar cell can be any one of a back-passivated solar cell, a passivated contact solar cell, and a back-contact solar cell.

[0170] It should be noted that the dielectric layer of the present application is arranged close to the surface of the P-type substrate or N-type substrate of the solar cell, and is used for chemical passivation and field passivation of the surface of the P-type substrate or N-type substrate, which can effectively suppress the recombination and compound loss on the surface of the P-type substrate or N-type substrate and improve the photoelectric conversion efficiency.

[0171] In some embodiments, the P-type substrate includes any one of a P-type silicon wafer, a P-type epitaxially grown doped layer, and a P-type diffusion layer. A P-type silicon wafer refers to single crystal silicon doped with a Group III element, including but not limited to boron, aluminum, and gallium. A P-type diffusion layer refers to a diffusion layer formed by diffusing a Group III element into an N-type silicon wafer, wherein the N-type silicon wafer refers to single crystal silicon doped with a Group V element, including but not limited to nitrogen, phosphorus, and arsenic. A P-type epitaxially grown doped layer refers to one or more layers of a polysilicon layer, a silicon carbide layer, a silicon nitride layer, or a silicon oxide layer doped with a Group III element.

[0172] In some embodiments, the N-type substrate includes an N-type silicon wafer. It should be noted that the N-type substrate in the embodiments of the present application does not include an N-type diffusion layer and an N-type epitaxial growth doping layer.

[0173] For example, the P-type silicon wafer can be single crystal silicon doped with boron, the P-type diffusion layer can be a diffusion layer diffused with high or low concentrations of boron, and the P-type epitaxial growth doped layer can be a boron-doped polysilicon layer. The N-type silicon wafer can be single crystal silicon doped with phosphorus.

[0174] Furthermore, the surface of the P-type substrate or the N-type substrate refers to the front side or the back side, the front side refers to the light incident side, and the back side refers to the side opposite to the light incident side. The dielectric layer can be arranged on the front side or the back side alone, or the dielectric layer can be arranged on the front side or the back side at the same time. The dielectric layer of the embodiment of the present application can be applied to the front side or the back side of various P-type substrates or N-type substrates of various solar cells, and can achieve effective field passivation and chemical passivation on the front side or the back side of a variety of solar cells, and can increase the refractive index of the front side or the back side to thereby improve the anti-reflection effect. The following will illustrate the setting position of the dielectric layer of the present application with reference to a specific schematic diagram.

[0175] Referring to FIG. 2 , an embodiment of the present application provides a PERC solar cell 100 (Passivated Emitter and Rear Cell).

[0176] When the dielectric layer is a single-layer aluminum oxynitride layer, the back-side passivated solar cell 100 includes:

[0177] A first P-type silicon wafer 11, the first P-type silicon wafer 11 having a first surface and a second surface disposed opposite to each other, the first surface being a light incident surface;

[0178] An N-type diffusion layer 12, the N-type diffusion layer 12 is provided on the first surface;

[0179] A first passivation layer 13, which is provided on a side of the N-type diffusion layer 12 facing away from the first P-type silicon wafer 11;

[0180] A first protective layer 14, which is provided on a side of the first passivation layer 13 facing away from the first P-type silicon wafer 11;

[0181] a dielectric layer 15, which is an aluminum oxynitride layer and is disposed on the second surface;

[0182] A second protective layer 16 , which is disposed on a side of the aluminum oxynitride layer 15 facing away from the first P-type silicon wafer 11 ; and

[0183] The first electrode structure includes a first electrode 171 and a second electrode 172 . The first electrode 171 is in ohmic contact with the first P-type silicon wafer 11 , and the second electrode 172 is in ohmic contact with the N-type diffusion layer 12 .

[0184] Referring to FIG3 , when the dielectric layer is an aluminum oxide layer and an aluminum oxynitride layer stacked in sequence, the back-side passivated solar cell 100 includes:

[0185] A first P-type silicon wafer 11, the first P-type silicon wafer 11 having a first surface and a second surface disposed opposite to each other, the first surface being a light incident surface;

[0186] An N-type diffusion layer 12, the N-type diffusion layer 12 is provided on the first surface;

[0187] A first passivation layer 13, which is provided on a side of the N-type diffusion layer 12 facing away from the first P-type silicon wafer 11;

[0188] A first protective layer 14, which is provided on a side of the first passivation layer 13 facing away from the first P-type silicon wafer 11;

[0189] The dielectric layer 15 includes an aluminum oxide layer 151 and an aluminum oxynitride layer 152 stacked in sequence; the aluminum oxide layer 151 is provided on the second surface;

[0190] A second protective layer 16 , which is disposed on a side of the aluminum oxynitride layer 152 facing away from the first P-type silicon wafer 11 ; and

[0191] The first electrode structure includes a first electrode 171 and a second electrode 172 . The first electrode 171 is in ohmic contact with the first P-type silicon wafer 11 , and the second electrode 172 is in ohmic contact with the N-type diffusion layer 12 .

[0192] For example, in a back-passivated solar cell, the first passivation layer 13 may be a silicon oxide layer, the first protective layer 14 may be a silicon nitride layer, a silicon oxynitride layer, etc., and the second protective layer 16 may be a silicon nitride layer, a silicon oxynitride layer, etc.

[0193] Referring to FIG. 4 , an embodiment of the present application provides a TOPCon solar cell 200 (Tunnel Oxide Passivating Contacts, passivated contact solar cell).

[0194] When the dielectric layer is a single-layer aluminum oxynitride layer, the passivated contact solar cell 200 includes:

[0195] A first N-type silicon wafer 21, wherein the first N-type silicon wafer 21 has a third surface and a fourth surface opposite to the third surface, wherein the third surface is a light incident surface;

[0196] A P-type diffusion layer 22, which is provided on the third surface;

[0197] A dielectric layer 23, which is an aluminum oxynitride layer. The aluminum oxynitride layer 23 is disposed on a side of the P-type diffusion layer 22 facing away from the first N-type silicon wafer 21;

[0198] A third protective layer 24 is provided on a side of the aluminum oxynitride layer 23 facing away from the first N-type silicon wafer 21;

[0199] A first tunneling oxide layer 25, the first tunneling oxide layer 25 is provided on the fourth surface;

[0200] A first doped polysilicon layer 26 , which is disposed on a side of the first tunneling oxide layer 25 facing away from the first N-type silicon wafer 21 ;

[0201] a first anti-reflection layer 27 , which is disposed on a side of the first doped polysilicon layer 26 facing away from the first N-type silicon wafer 21 ; and

[0202] The second electrode structure includes a third electrode 281 and a fourth electrode 282 . The third electrode 281 is in ohmic contact with the P-type diffusion layer 22 , and the fourth electrode 282 is in ohmic contact with the first doped polysilicon layer 26 .

[0203] Referring to FIG. 5 , when the dielectric layer is an aluminum oxide layer and an aluminum oxynitride layer stacked sequentially, the passivated contact solar cell 200 includes:

[0204] A first N-type silicon wafer 21, wherein the first N-type silicon wafer 21 has a third surface and a fourth surface opposite to the third surface, wherein the third surface is a light incident surface;

[0205] A P-type diffusion layer 22, which is provided on the third surface;

[0206] The dielectric layer 23 includes an aluminum oxide layer 231 and an aluminum oxynitride layer 232 stacked in sequence; the aluminum oxide layer 231 is provided on a side of the P-type diffusion layer 22 facing away from the first N-type silicon wafer 21;

[0207] A third protective layer 24 , which is disposed on a side of the aluminum oxynitride layer 232 facing away from the first N-type silicon wafer 21 ;

[0208] A first tunneling oxide layer 25, the first tunneling oxide layer 25 is provided on the fourth surface;

[0209] A first doped polysilicon layer 26 , which is disposed on a side of the first tunneling oxide layer 25 facing away from the first N-type silicon wafer 21 ;

[0210] a first anti-reflection layer 27 , which is disposed on a side of the first doped polysilicon layer 26 facing away from the first N-type silicon wafer 21 ; and

[0211] The second electrode structure includes a third electrode 281 and a fourth electrode 282 . The third electrode 281 is in ohmic contact with the P-type diffusion layer 22 , and the fourth electrode 282 is in ohmic contact with the first doped polysilicon layer 26 .

[0212] For example, in a passivated contact solar cell, the third protective layer 24 may be a silicon nitride layer, a silicon oxynitride layer, etc., and the first anti-reflection layer may be a silicon nitride layer, a silicon oxynitride layer, etc.

[0213] Please refer to FIG. 6 . The present application provides an N-type IBC solar cell 300 (Interdigitated back contact, N-type back contact solar cell).

[0214] When the dielectric layer is a single-layer aluminum oxynitride layer, the N-type back contact solar cell 300 includes:

[0215] a second N-type silicon wafer 31, wherein the second N-type silicon wafer 31 has a fifth surface and a sixth surface opposite to the fifth surface, wherein the fifth surface is a light incident surface;

[0216] A second passivation layer 32, the second passivation layer 32 is provided on the fifth surface;

[0217] a fourth protective layer 33 , which is disposed on a side of the second passivation layer 32 facing away from the second N-type silicon wafer 31 ;

[0218] A second tunnel oxide layer 34 , the second tunnel oxide layer 34 including a first portion 341 and a second portion 342 , wherein the first portion 341 and the second portion 342 are disposed on the sixth surface;

[0219] a second doped polysilicon layer, the second doped polysilicon layer comprising a P-type doped polysilicon layer 351 and an N-type doped polysilicon layer 352, the P-type doped polysilicon layer 351 being disposed on a side of the first portion 341 facing away from the second N-type silicon wafer 31, and the N-type doped polysilicon layer 352 being disposed on a side of the second portion 342 facing away from the second N-type silicon wafer 31;

[0220] Dielectric layer 36, which is an aluminum oxynitride layer. Dielectric layer 36 includes a third portion 361, a fourth portion 362, and a fifth portion 363. Third portion 361 is provided on a side of the P-type doped polysilicon layer 351 facing away from the second N-type silicon wafer 31. Fourth portion 362 is provided on the sixth side and between the P-type doped polysilicon layer 351 and the N-type doped polysilicon layer 352. Fifth portion 363 is provided on a side of the N-type doped polysilicon layer 352 facing away from the second N-type silicon wafer 31.

[0221] a fifth protective layer 37 , which is disposed on a surface of the third portion 361 , the fourth portion 362 , and the fifth portion 363 facing away from the second N-type silicon wafer 31 ; and

[0222] The third electrode structure includes a fifth electrode 381 and a sixth electrode 382 . The fifth electrode 381 is in ohmic contact with the P-type doped polysilicon layer 351 , and the sixth electrode 382 is in ohmic contact with the N-type doped polysilicon layer 352 .

[0223] Referring to FIG. 7 , when the dielectric layer is an aluminum oxide layer and an aluminum oxynitride layer stacked sequentially, the N-type back-contact solar cell 300 includes:

[0224] a second N-type silicon wafer 31, wherein the second N-type silicon wafer 31 has a fifth surface and a sixth surface opposite to the fifth surface, wherein the fifth surface is a light incident surface;

[0225] A second passivation layer 32, the second passivation layer 32 is provided on the fifth surface;

[0226] a fourth protective layer 33 , which is disposed on a side of the second passivation layer 32 facing away from the second N-type silicon wafer 31 ;

[0227] A second tunnel oxide layer 34 , the second tunnel oxide layer 34 including a first portion 341 and a second portion 342 , wherein the first portion 341 and the second portion 342 are disposed on the sixth surface;

[0228] a second doped polysilicon layer, the second doped polysilicon layer comprising a P-type doped polysilicon layer 351 and an N-type doped polysilicon layer 352, the P-type doped polysilicon layer 351 being disposed on a side of the first portion 341 facing away from the second N-type silicon wafer 31, and the N-type doped polysilicon layer 352 being disposed on a side of the second portion 342 facing away from the second N-type silicon wafer 31;

[0229] The dielectric layer 36 includes a third portion 361 , a fourth portion 362 , and a fifth portion 363 ;

[0230] The third portion 361 includes a first aluminum oxide layer 3611 and a first aluminum oxynitride layer 3612 stacked in sequence. The first aluminum oxide layer 3611 is provided on a side of the P-type doped polysilicon layer 351 facing away from the second N-type silicon wafer 31 .

[0231] The fourth portion 362 includes a second aluminum oxide layer 3621 and a second aluminum oxynitride layer 3622 stacked in sequence. The second aluminum oxide layer 3621 is provided on the sixth surface and between the P-type doped polysilicon layer 351 and the N-type doped polysilicon layer 352.

[0232] The fifth portion 363 includes a third aluminum oxide layer 3631 and a third aluminum oxynitride layer 3632 stacked in sequence, wherein the third aluminum oxide layer 3631 is disposed on a side of the N-type doped polysilicon layer 352 facing away from the second N-type silicon wafer 31 ; and

[0233] a fifth protective layer 37 , which is disposed on a surface of the first aluminum oxynitride layer 3612 , the second aluminum oxynitride layer 3622 , and the third aluminum oxynitride layer 3632 facing away from the second N-type silicon wafer 31 ; and

[0234] The third electrode structure includes a fifth electrode 381 and a sixth electrode 382 . The fifth electrode 381 is in ohmic contact with the P-type doped polysilicon layer 351 , and the sixth electrode 382 is in ohmic contact with the N-type doped polysilicon layer 352 .

[0235] For example, in an N-type back-contact solar cell, the second passivation layer 32 may be an aluminum oxynitride layer, an aluminum oxide layer, a silicon dioxide layer, etc., the fourth protective layer 33 may be a silicon nitride layer, etc., and the fifth protective layer 37 may be a silicon nitride layer, etc.

[0236] Furthermore, the second passivation layer 32 may be an aluminum oxynitride layer. When the second passivation layer 32 is an aluminum oxynitride layer, due to its higher hydrogen content, it has a better hydrogen passivation effect than silicon dioxide. In addition, compared with silicon dioxide, silicon oxynitride has less passivation quality degradation under ultraviolet radiation, has better UV resistance and stability, and has better long-term stability for solar cells. The fifth and sixth surfaces of the second N-type silicon wafer are simultaneously provided with a film layer containing an aluminum oxynitride layer, which greatly improves the passivation effect on the front and back of the N-type back-contact solar cell, which is beneficial to improving the photoelectric conversion efficiency.

[0237] Please refer to FIG. 8 . The present application provides a P-type IBC solar cell 400 (Interdigitated back contact, P-type back contact solar cell).

[0238] When the dielectric layer is a single-layer aluminum oxynitride layer, the P-type back contact solar cell 400 includes:

[0239] a second P-type silicon wafer 41, the second P-type silicon wafer 41 having a seventh surface and an eighth surface opposite to the seventh surface, the seventh surface being a light incident surface;

[0240] A third passivation layer 42, the third passivation layer 42 is provided on the seventh surface;

[0241] a sixth protective layer 43 , which is disposed on a side of the third passivation layer 42 facing away from the second P-type silicon wafer 41 ;

[0242] A third tunneling oxide layer 44, the third tunneling oxide layer 44 is provided on the eighth surface;

[0243] An N-type doped polysilicon layer 45 , which is disposed on a side of the third tunneling oxide layer 44 facing away from the second P-type silicon wafer 41 ;

[0244] Dielectric layer 46 , which is an aluminum oxynitride layer. Dielectric layer 46 includes a sixth portion 461 and a seventh portion 462 . Sixth portion 461 is provided on the eighth surface, and seventh portion 462 is provided on a surface of the N-type doped polysilicon layer 45 facing away from the second P-type silicon wafer 41 .

[0245] a seventh protective layer 47 , which is disposed on a side of the sixth portion 461 and the seventh portion 462 facing away from the second N-type silicon wafer 41 ; and

[0246] The fourth electrode structure includes a seventh electrode 481 and an eighth electrode 482 . The seventh electrode 481 is in ohmic contact with the second P-type silicon wafer 41 , and the eighth electrode 482 is in ohmic contact with the N-type doped polysilicon layer 45 .

[0247] Referring to FIG. 9 , when the dielectric layer is an aluminum oxide layer and an aluminum oxynitride layer stacked sequentially, the P-type back-contact solar cell 300 includes:

[0248] a second P-type silicon wafer 41, the second P-type silicon wafer 41 having a seventh surface and an eighth surface opposite to the seventh surface, the seventh surface being a light incident surface;

[0249] A third passivation layer 42, the third passivation layer 42 is provided on the seventh surface;

[0250] a sixth protective layer 43 , which is disposed on a side of the third passivation layer 42 facing away from the second P-type silicon wafer 41 ;

[0251] A third tunneling oxide layer 44, the third tunneling oxide layer 44 is provided on the eighth surface;

[0252] An N-type doped polysilicon layer 45 , which is disposed on a side of the third tunneling oxide layer 44 facing away from the second P-type silicon wafer 41 ;

[0253] The dielectric layer 46 includes a sixth portion 461 and a seventh portion 462 ;

[0254] The sixth portion 461 includes a fourth aluminum oxide layer 4611 and a fourth aluminum oxynitride layer 4612 stacked in sequence, and the fourth aluminum oxide layer 4611 is provided on the eighth surface;

[0255] The seventh portion 462 includes a fifth aluminum oxide layer 4621 and a fifth aluminum oxynitride layer 4622 stacked in sequence. The fifth aluminum oxide layer 4621 is provided on a side of the N-type doped polysilicon layer 45 facing away from the second P-type silicon wafer 41 .

[0256] a seventh protective layer 47 , which is disposed on a side of the fourth aluminum oxynitride layer 4612 and the fifth aluminum oxynitride layer 4622 facing away from the second N-type silicon wafer 41 ; and

[0257] The fourth electrode structure includes a seventh electrode 481 and an eighth electrode 482 . The seventh electrode 481 is in ohmic contact with the second P-type silicon wafer 41 , and the eighth electrode 482 is in ohmic contact with the N-type doped polysilicon layer 45 .

[0258] For example, in a P-type back-contact solar cell, the third passivation layer 42 may be an aluminum oxynitride layer, an aluminum oxide layer, a silicon dioxide layer, etc., the fourth protective layer 43 may be a silicon nitride layer, etc., and the seventh protective layer 47 may be a silicon nitride layer, etc.

[0259] Furthermore, the third passivation layer 42 may be an aluminum oxynitride layer. When the third passivation layer 42 is an aluminum oxynitride layer, due to its higher hydrogen content, it has a better hydrogen passivation effect than silicon dioxide. In addition, compared with silicon dioxide, silicon oxynitride has less passivation quality degradation under ultraviolet radiation, has better UV resistance and stability, and has better long-term stability for solar cells. The fifth and sixth surfaces of the second N-type silicon wafer are simultaneously provided with a film layer containing an aluminum oxynitride layer, which greatly improves the passivation effect on the front and back sides of the N-type back-contact solar cell, which is beneficial to improving the photoelectric conversion efficiency.

[0260] As can be seen from the structures of solar cells 100, 200, 300, and 400, when a dielectric layer is applied to a solar cell, it must contact various P-type or N-type substrates, and a protective layer must be provided on the other side of the dielectric layer. The protective layer protects the dielectric layer from damage during the high-temperature firing process used to form the electrodes and also acts as an anti-reflection layer to enhance the solar cell's absorption of incident light.

[0261] In some embodiments, the protective layer may be deposited by chemical vapor deposition, for example, by chemical vapor deposition methods such as LPCVD (Low Pressure CVD), RFCVD (Radio Frequency CVD), and PECVD (Plasma Enhanced CVD).

[0262] In some embodiments, the protective layer includes a combination of one or more of silicon nitride, silicon oxynitride, silicon oxide, and silicon carbide. That is, the protective layer can be a single layer formed of a single material or a multilayer formed of multiple materials. The protective layer in the embodiment of the present application includes a first protective layer, a second protective layer, a third protective layer, a fourth protective layer, a fifth protective layer, a sixth protective layer, and a seventh protective layer.

[0263] In some embodiments, the protective layer contains hydrogen greater than or equal to 1 wt %, which can further chemically passivate the suspension component and reduce surface defects.

[0264] In some embodiments, the thickness of the protective layer is greater than or equal to 50 nm, and the thickness of the dielectric layer is less than 30 nm, such that the sum of the thicknesses of the dielectric layer and the protective layer is 75 nm to 85 nm. This maximizes the refractive index, better utilizes the interference effect of light, and enhances the anti-reflection effect between the dielectric layer and the protective layer. For example, the sum of the thicknesses can be any value within the above range, such as 75 nm, 76 nm, 77 nm, 78 nm, 79 nm, 80 nm, 81 nm, 82 nm, 83 nm, 84 nm, and 85 nm.

[0265] In a fourth aspect, the present application provides a photovoltaic assembly, which includes the solar cells according to the third aspect. The solar cells can be connected in series or in parallel to form the photovoltaic assembly.

[0266] In a fifth aspect, the present application also provides a photovoltaic device, which includes the photovoltaic component of the fourth aspect. The photovoltaic device can be a centralized photovoltaic power station, a distributed photovoltaic power station, a transportation photovoltaic power station, etc.

[0267] The technical solution of the present application will be further described below with reference to specific embodiments and comparative examples:

[0268] Example 1

[0269] Referring to FIG3 , a first embodiment provides a back-side passivated solar cell 100 having a composite dielectric layer. The back-side passivated solar cell 100 includes:

[0270] A first P-type silicon wafer 11, the first P-type silicon wafer 11 having a first surface and a second surface disposed opposite to each other, the first surface being a light incident surface;

[0271] An N-type diffusion layer 12, the N-type diffusion layer 12 is provided on the first surface;

[0272] A first passivation layer 13, which is provided on a side of the N-type diffusion layer 12 facing away from the first P-type silicon wafer 11;

[0273] A first protective layer 14, which is provided on a side of the first passivation layer 13 facing away from the first P-type silicon wafer 11;

[0274] The dielectric layer 15 includes an aluminum oxide layer 151 and an aluminum oxynitride layer 152 stacked in sequence; the aluminum oxide layer 151 is provided on the second surface;

[0275] A second protective layer 16 , which is disposed on a side of the aluminum oxynitride layer 152 facing away from the first P-type silicon wafer 11 ; and

[0276] The first electrode structure includes a first electrode 171 and a second electrode 172 . The first electrode 171 is in ohmic contact with the first P-type silicon wafer 11 , and the second electrode 172 is in ohmic contact with the N-type diffusion layer 12 .

[0277] This embodiment also provides a method for preparing the above-mentioned back-passivated solar cell 100, which comprises the following steps:

[0278] Texturing: In a tank-type device, sodium hydroxide and TS40 additive were used in a volume ratio of 7:1, the temperature was maintained at 80°C, and the time was 7 minutes to texturing M10 silicon wafers, and the thinning amount was controlled at 5μm.

[0279] Boron diffusion: Place the silicon wafer after texturing into a phosphorus diffusion furnace. Use nitrogen to carry phosphorus oxychloride (POCl3) gas and oxygen (O2) in a volume ratio of 2:1. Deposit the boron source at 780°C, and then push it at 840°C for 15 minutes to form a PN junction.

[0280] Laser forms selective heavy doping: A 532nm nanosecond laser is used with 40W of energy to create the same pattern on the front of the silicon wafer as on the front of the silk screen. The area scanned by the laser is the heavily doped area.

[0281] Chain oxidation: Place the first side of the silicon wafer facing up and pass it through the chain oxidation equipment at a temperature of 650°C. Control the oxygen flow rate to 40SLM and the passing time to 1 minute to form an oxide layer on the heavily doped area just hit by the laser.

[0282] Alkali polishing: Use a chain HF machine and a 20% volume percentage hydrofluoric acid solution to remove the phosphosilicate glass layer on the back side of the phosphorus expansion layer. Then transfer it to a tank-type alkali polishing machine through a robot, use sodium hydroxide NaOH and alkali polishing additive BP31 with a volume ratio of 3:1, a temperature of 80°C, and a time of 7 minutes to polish the back side and simultaneously remove the PN junction plated to the back and edge during the boron expansion step; finally transfer it to an acid tank and use hydrofluoric acid with a mass concentration of 5% to remove the phosphosilicate glass layer on the front side and the oxide layer above the heavily doped area.

[0283] Front thermal oxidation: Use a tubular oxidation furnace to place the silicon wafer with the first side facing outward in a quartz boat and oxidize for 20 minutes at an oxygen flow rate of 10 SLM.

[0284] Deposition of dielectric layer: First, use tubular ALD equipment, process temperature is 350℃, control gas flow rate is 50sccm, first deposit aluminum oxide layer, then deposit aluminum oxynitride layer. Specifically include:

[0285] ① Deposition of aluminum oxide layer: First, introduce Al(CH3)3 gas for 10 seconds, evacuate for 10 seconds, then introduce H2O gas for 10 seconds, and evacuate for 10 seconds. After the above two gases are introduced and evacuated in sequence, it is considered a growth cycle. The above cycle is repeated 5 times in total to deposit a 2nm thick aluminum oxide layer.

[0286] ② Deposition of aluminum oxynitride layer: The number of growth cycles with aluminum and oxygen sources was maintained at 5: In one growth cycle, Al(CH3)3 gas was introduced for 10 seconds, the atmosphere was evacuated for 10 seconds, then H2O gas was introduced for 10 seconds, and the atmosphere was evacuated for 10 seconds. The number of growth cycles with aluminum, oxygen, and nitrogen sources was increased to 15: In one growth cycle, Al(CH3)3 gas was introduced for 10 seconds, the atmosphere was evacuated for 10 seconds, then H2O gas was introduced for 10 seconds, the atmosphere was evacuated for 10 seconds, and finally NH3 gas was introduced for 20 seconds, and the atmosphere was evacuated for 10 seconds. Thus, a total of 25 growth cycles were performed to deposit a 3 nm thick aluminum oxynitride layer.

[0287] Deposition of the second protective layer: The silicon wafer is transported to another tubular PECVD device, where three layers of silicon nitride are deposited on the back side of the wafer. The wafer is first placed in a graphite boat, with the first side of the wafer facing the boat and the back side facing outward. The temperature inside the reactor tube is then raised to 550°C, and the chamber is held in a nitrogen atmosphere for 15 minutes. The pressure is then reduced to 2000 mTorr to deposit the protective layer, which consists of three layers of silicon nitride. The total deposition time is 60 minutes, and the total thickness of the protective layer is 55 nm. The combined thickness of the dielectric and protective layers is 60 nm.

[0288] Front first passivation layer deposition: In a tubular PECVD device, silicon nitride layer, silicon oxynitride and silicon oxide layer are deposited in sequence with a total thickness of 80nm.

[0289] Back-side laser grooving: Using a 532nm nanosecond green laser, a back-side silkscreen pattern is created on the back side with a duty cycle of 0.5:0.5, removing the back-side film layer in the corresponding area to allow the metallization paste to form contact with the P-type silicon wafer.

[0290] Screen printing: Print aluminum paste on the back and complete the production of the first electrode at a sintering process temperature of 800°C. Print silver paste on the front and complete the production of the second electrode at a sintering process temperature of 800°C. Complete the electrical injection into the battery at a process temperature of 200°C.

[0291] Example 2

[0292] 2 , the second embodiment also provides a back-side passivated solar cell 100 , in which the dielectric layer 15 of the back-side passivated solar cell 100 is an aluminum oxynitride layer. Similarly, in the preparation method of the back-side passivated solar cell 100 , the aluminum oxynitride layer is deposited by ALD, and the rest remains the same as in the first embodiment.

[0293] Example 3

[0294] Referring to FIG. 5 , a third embodiment provides a passivated contact solar cell 200 having a composite dielectric layer. The passivated contact solar cell 200 includes:

[0295] A first N-type silicon wafer 21, wherein the first N-type silicon wafer 21 has a third surface and a fourth surface opposite to the third surface, wherein the third surface is a light incident surface;

[0296] A P-type diffusion layer 22, which is provided on the third surface;

[0297] The dielectric layer 23 includes an aluminum oxide layer 231 and an aluminum oxynitride layer 232 stacked in sequence; the aluminum oxide layer 231 is provided on a side of the P-type diffusion layer 22 facing away from the first N-type silicon wafer 21;

[0298] A third protective layer 24 , which is disposed on a side of the aluminum oxynitride layer 232 facing away from the first N-type silicon wafer 21 ;

[0299] A first tunneling oxide layer 25, the first tunneling oxide layer 25 is provided on the fourth surface;

[0300] A first doped polysilicon layer 26 , which is disposed on a side of the first tunneling oxide layer 25 facing away from the first N-type silicon wafer 21 ;

[0301] a first anti-reflection layer 27 , which is disposed on a side of the first doped polysilicon layer 26 facing away from the first N-type silicon wafer 21 ; and

[0302] The second electrode structure includes a third electrode 281 and a fourth electrode 282 . The third electrode 281 is in ohmic contact with the P-type diffusion layer 22 , and the fourth electrode 282 is in ohmic contact with the first doped polysilicon layer 26 .

[0303] This embodiment also provides a method for preparing a passivated contact solar cell 200, the preparation steps comprising:

[0304] Texturing: In a tank-type device, sodium hydroxide and TS40 additives were used in a volume ratio of 7:1, the temperature was maintained at 80°C, and the time was 7 minutes to texturing N-type M10 silicon wafers, and the thinning amount was controlled at 5μm.

[0305] Boron diffusion: Place the silicon wafer after texturing into a boron diffusion furnace, use boron trichloride gas and oxygen in a volume ratio of 1:3, deposit the boron source at 830°C, and then push it at 1030°C for 1 hour to form a PN junction.

[0306] Alkali polishing: Use a chain HF machine and a 50% by volume hydrofluoric acid solution to remove the borosilicate glass with boron expansion on the back side. Then transfer it to a tank-type alkali polishing machine through a robot. Use sodium hydroxide and alkali polishing additive BP31 in a volume ratio of 3:1. Maintain the temperature at 80°C for 7 minutes to polish the back side and remove the PN junction plated to the back and edge during the boron expansion step.

[0307] Fabrication of the first tunneling oxide layer and the first doped polysilicon layer on the back side: Using a tubular PECVD device, at a pressure of 3000mTorr, the first tunneling oxide layer, silicon oxide layer, intrinsic amorphous silicon layer, phosphorus-doped amorphous silicon layer and silicon oxynitride mask layer are deposited on the back side of the silicon wafer.

[0308] Annealing: A tubular annealing furnace was used to anneal the silicon wafer. The comparative gas atmosphere was nitrogen, the nitrogen was 10 SLM, the temperature was 900°C, the time was 120 minutes, and the annealing time was 2700 seconds, so that the crystal structure of the deposited amorphous silicon layer was transformed to form a polycrystalline silicon layer.

[0309] RCA cleaning: First, it passes through a chain device and uses hydrofluoric acid with a mass concentration of 5% to remove the oxide layer on one side of the front side. Then, it is transferred to a tank-type alkaline polishing machine through a robot arm, using sodium hydroxide NaOH and alkaline polishing additive BP31 with a volume ratio of 2:1. The temperature is maintained at 80°C for 2 minutes to remove the polysilicon thin film layer that was deposited on the front side during the annealing step. Finally, it is transferred to an acid tank and uses hydrofluoric acid with a mass concentration of 5% to remove the borosilicate glass layer on the front side and the mask layer on the back side.

[0310] Deposition of dielectric layer: First, using tubular ALD equipment, the process temperature is 350°C, and the gas flow rate is controlled at 50 sccm. On the front boron diffusion surface of the N-type silicon wafer, an aluminum oxide layer is first deposited, followed by an aluminum oxynitride layer. Specifically, it includes:

[0311] ① Deposition of aluminum oxide layer: First, introduce Al(CH3)3 gas for 10 seconds, evacuate for 10 seconds, then introduce H2O gas for 10 seconds, and evacuate for 10 seconds. After the above two gases are introduced and evacuated in sequence, it is considered a growth cycle. The above cycle is repeated 3 times in total to deposit an aluminum oxide layer with a thickness of 1 nm.

[0312] ② Deposition of aluminum oxynitride layer: The number of growth cycles with aluminum and oxygen sources was maintained at 15: During one growth cycle, Al(CH3)3 gas was introduced for 10 seconds, the atmosphere was evacuated for 10 seconds, then H2O gas was introduced for 10 seconds, and the atmosphere was evacuated for 10 seconds. The number of growth cycles with aluminum, oxygen, and nitrogen sources was maintained at 15: During one growth cycle, Al(CH3)3 gas was introduced for 10 seconds, the atmosphere was evacuated for 10 seconds, then H2O gas was introduced for 10 seconds, and the atmosphere was evacuated for 10 seconds, and finally NH3 gas was introduced for 20 seconds, and the atmosphere was evacuated for 10 seconds. Thus, a total of 30 growth cycles were performed to deposit a 5 nm thick aluminum oxynitride layer.

[0313] Deposition of the protective layer: The silicon wafer is transported to another tubular PECVD system, where a protective layer composed of silicon nitride and silicon oxynitride is deposited on the back side of the wafer. The wafer is first loaded into a graphite boat, with the back side of the wafer against the boat and the front side facing outward. The temperature inside the reactor tube is then raised to 550°C and held in a nitrogen atmosphere for 15 minutes. The pressure is then reduced to 2000 mTorr, where the silicon nitride and silicon oxynitride layers are deposited. The total coating process takes 50 minutes, resulting in a total protective layer thickness of 74nm and a 5% hydrogen content. The combined thickness of the dielectric and protective layers is 80nm.

[0314] Deposition of the first anti-reflection layer: PECVD is used to deposit a silicon nitride layer with a thickness of 80 nm.

[0315] Screen printing: Printing silver paste on the back side at a sintering process temperature of 840°C to complete the preparation of the fourth electrode, printing silver aluminum paste on the front side at a sintering process temperature of 840°C to complete the production of the third electrode; at a process temperature of 700°C, complete the light injection into the passivated contact solar cell.

[0316] Example 4

[0317] Please refer to Figure 4. Example 4 also provides a passivated contact solar cell 200. The dielectric layer 23 of the passivated contact solar cell 200 is an aluminum oxynitride layer. Similarly, in the preparation method of the passivated contact solar cell 200, the aluminum oxynitride layer is deposited by ALD method, and the rest is consistent with Example 1.

[0318] Example 5

[0319] The fifth embodiment provides a back-passivated solar cell. The difference from the first embodiment is that in the step of preparing the aluminum oxynitride layer, the aluminum source, oxygen source and nitrogen source are introduced simultaneously 20 times.

[0320] Example 6

[0321] The sixth embodiment provides a back-passivated solar cell. The difference from the first embodiment is that, in the step of preparing the aluminum oxynitride layer, the aluminum source, oxygen source and nitrogen source are introduced simultaneously 25 times.

[0322] Example 7

[0323] Referring to FIG. 9 , a seventh embodiment provides a P-type IBC solar cell 400 having a composite dielectric layer. The P-type IBC solar cell 400 includes:

[0324] a second P-type silicon wafer 41, the second P-type silicon wafer 41 having a seventh surface and an eighth surface opposite to the seventh surface, the seventh surface being a light incident surface;

[0325] A third passivation layer 42, the third passivation layer 42 is provided on the seventh surface;

[0326] a sixth protective layer 43 , which is disposed on a side of the third passivation layer 42 facing away from the second P-type silicon wafer 41 ;

[0327] A third tunneling oxide layer 44, the third tunneling oxide layer 44 is provided on the eighth surface;

[0328] An N-type doped polysilicon layer 45 , which is disposed on a side of the third tunneling oxide layer 44 facing away from the second P-type silicon wafer 41 ;

[0329] The dielectric layer 46 includes a sixth portion 461 and a seventh portion 462 ;

[0330] The sixth portion 461 includes a fourth aluminum oxide layer 4611 and a fourth aluminum oxynitride layer 4612 stacked in sequence, and the fourth aluminum oxide layer 4611 is provided on the eighth surface;

[0331] The seventh portion 462 includes a fifth aluminum oxide layer 4621 and a fifth aluminum oxynitride layer 4622 stacked in sequence. The fifth aluminum oxide layer 4621 is provided on a side of the N-type doped polysilicon layer 45 facing away from the second P-type silicon wafer 41 .

[0332] a seventh protective layer 47 , which is disposed on a side of the fourth aluminum oxynitride layer 4612 and the fifth aluminum oxynitride layer 4622 facing away from the second N-type silicon wafer 41 ; and

[0333] The fourth electrode structure includes a seventh electrode 481 and an eighth electrode 482 . The seventh electrode 481 is in ohmic contact with the second P-type silicon wafer 41 , and the eighth electrode 482 is in ohmic contact with the N-type doped polysilicon layer 45 .

[0334] This embodiment also provides a method for preparing a P-type IBC solar cell 400, the preparation steps comprising:

[0335] Polishing: P-type M10 silicon wafers were double-sided polished in a tank-type equipment using sodium hydroxide and alkaline polishing additive BP31 in a volume ratio of 3:1 at 80°C for 7 minutes.

[0336] Fabrication of the first tunneling oxide layer and the first doped polysilicon layer on the back side: Using a tubular PECVD device, at a pressure of 3000mTorr, the first tunneling oxide layer, silicon oxide layer, intrinsic amorphous silicon layer, phosphorus-doped amorphous silicon layer and silicon oxynitride mask layer are deposited on the back side of the silicon wafer.

[0337] Annealing: A tubular annealing furnace was used to anneal the silicon wafer. The comparative gas atmosphere was nitrogen, the nitrogen was 10 SLM, the temperature was 900°C, the time was 120 minutes, and the annealing time was 2700 seconds, so that the crystal structure of the deposited amorphous silicon layer was transformed to form a polycrystalline silicon layer.

[0338] Laser grooving: Using a 532nm nanosecond laser with 40W of energy, the deposited polysilicon layer on the back of the silicon wafer is removed to form a P-type area with a specific pattern. The area not lasered is the N-type area.

[0339] Texturing: A chain HF machine is used with a 50% by volume hydrofluoric acid solution to remove the silicon oxynitride mask layer that was plated onto the front side during the poly deposition process. The device is then transferred to a tank texturing machine via a robot. Sodium hydroxide and a TS40 additive are used in a volume ratio of 7:1. The temperature is maintained at 80°C for 7 minutes for texturing. The N-type area on the back side that has not been lasered is not affected due to the protection of the silicon oxynitride mask layer, while the lasered areas on the front and back sides will grow a texturing surface.

[0340] Deposition of dielectric layer: First, a tubular ALD device is used to deposit the dielectric layer on both sides. The process temperature is 270°C, and the gas flow rate is controlled at 50 sccm. First, the aluminum oxide layer is deposited, and then the aluminum oxynitride layer is deposited. Specifically, it includes:

[0341] ① Deposition of aluminum oxide layer: First, introduce Al(CH3)3 gas for 10 seconds, evacuate for 10 seconds, then introduce H2O gas for 10 seconds, and evacuate for 10 seconds. After the above two gases are introduced and evacuated in sequence, it is considered a growth cycle. The above cycle is repeated 5 times in total to deposit a 2nm thick aluminum oxide layer.

[0342] ② Deposition of aluminum oxynitride layer: The number of growth cycles with aluminum and oxygen sources was maintained at 15: During one growth cycle, Al(CH3)3 gas was introduced for 10 seconds, the atmosphere was evacuated for 10 seconds, then H2O gas was introduced for 10 seconds, and the atmosphere was evacuated for 10 seconds. The number of growth cycles with aluminum, oxygen, and nitrogen sources was maintained at 15: During one growth cycle, Al(CH3)3 gas was introduced for 10 seconds, the atmosphere was evacuated for 10 seconds, then H2O gas was introduced for 10 seconds, and the atmosphere was evacuated for 10 seconds, and finally NH3 gas was introduced for 20 seconds, and the atmosphere was evacuated for 10 seconds. Thus, a total of 30 growth cycles were performed to deposit a 4 nm thick aluminum oxynitride layer.

[0343] Deposition of the protective layer: The silicon wafer is transported to another tubular PECVD system, where a protective layer composed of silicon nitride and silicon oxynitride is deposited on the front side of the wafer. The wafer is first loaded into a graphite boat, with the back side of the wafer against the boat and the front side facing outward. The temperature inside the reactor tube is then raised to 550°C and held in a nitrogen atmosphere for 15 minutes. The pressure is then reduced to 2000 mTorr, where the silicon nitride and silicon oxynitride layers are deposited. The total coating process takes 50 minutes, resulting in a total protective layer thickness of 74nm and a 5% hydrogen content. The combined thickness of the dielectric and protective layers is 80nm.

[0344] Deposition of the second protective layer: PECVD is used to deposit a silicon nitride layer with a thickness of 80nm on the back of the silicon wafer.

[0345] Screen printing: Printing aluminum paste on the back side at a sintering process temperature of 840°C to complete the preparation of the fourth electrode, and printing silver paste on the back side at a sintering process temperature of 840°C to complete the production of the third electrode; at a process temperature of 300°C, complete the light injection into the passivated contact solar cell.

[0346] Example 8

[0347] 8 , the eighth embodiment also provides a P-type IBC solar cell 400 . The dielectric layer 46 of the P-type IBC solar cell 400 is an aluminum oxynitride layer. Similarly, in the preparation method of the P-type IBC solar cell 400 , the aluminum oxynitride layer is deposited by ALD, and the rest is consistent with the seventh embodiment.

[0348] Embodiment 9

[0349] Referring to FIG. 7 , a seventh embodiment provides an N-type IBC solar cell 300 having a composite dielectric layer. The N-type IBC solar cell 400 includes:

[0350] a second N-type silicon wafer 31, wherein the second N-type silicon wafer 31 has a fifth surface and a sixth surface opposite to the fifth surface, wherein the fifth surface is a light incident surface;

[0351] A second passivation layer 32 is provided on the fifth surface, and the second passivation layer 32 is an aluminum oxynitride layer;

[0352] a fourth protective layer 33 , which is disposed on a side of the second passivation layer 32 facing away from the second N-type silicon wafer 31 ;

[0353] A second tunnel oxide layer 34 , the second tunnel oxide layer 34 including a first portion 341 and a second portion 342 , wherein the first portion 341 and the second portion 342 are disposed on the sixth surface;

[0354] a second doped polysilicon layer, the second doped polysilicon layer comprising a P-type doped polysilicon layer 351 and an N-type doped polysilicon layer 352, the P-type doped polysilicon layer 351 being disposed on a side of the first portion 341 facing away from the second N-type silicon wafer 31, and the N-type doped polysilicon layer 352 being disposed on a side of the second portion 342 facing away from the second N-type silicon wafer 31;

[0355] The dielectric layer 36 includes a third portion 361 , a fourth portion 362 , and a fifth portion 363 ;

[0356] The third portion 361 includes a first aluminum oxide layer 3611 and a first aluminum oxynitride layer 3612 stacked in sequence. The first aluminum oxide layer 3611 is provided on a side of the P-type doped polysilicon layer 351 facing away from the second N-type silicon wafer 31 .

[0357] The fourth portion 362 includes a second aluminum oxide layer 3621 and a second aluminum oxynitride layer 3622 stacked in sequence. The second aluminum oxide layer 3621 is provided on the sixth surface and between the P-type doped polysilicon layer 351 and the N-type doped polysilicon layer 352.

[0358] The fifth portion 363 includes a third aluminum oxide layer 3631 and a third aluminum oxynitride layer 3632 stacked in sequence, wherein the third aluminum oxide layer 3631 is disposed on a side of the N-type doped polysilicon layer 352 facing away from the second N-type silicon wafer 31 ; and

[0359] a fifth protective layer 37 , which is disposed on a surface of the first aluminum oxynitride layer 3612 , the second aluminum oxynitride layer 3622 , and the third aluminum oxynitride layer 3632 facing away from the second N-type silicon wafer 31 ; and

[0360] The third electrode structure includes a fifth electrode 381 and a sixth electrode 382 . The fifth electrode 381 is in ohmic contact with the P-type doped polysilicon layer 351 , and the sixth electrode 382 is in ohmic contact with the N-type doped polysilicon layer 352 .

[0361] This embodiment further provides a method for preparing an N-type IBC solar cell 300, the preparation steps comprising:

[0362] Polishing: Double-sided polishing of N-type M10 silicon wafers was performed in a tank-type equipment using sodium hydroxide and alkaline polishing additive BP31 in a volume ratio of 3:1 at 80°C for 7 minutes.

[0363] Deposition of intrinsic amorphous silicon 1: Using a tubular LPCVD device, at 565°C, the first tunneling oxide layer, silicon oxide layer, and intrinsic amorphous silicon layer are deposited on the back of the silicon wafer.

[0364] Boron diffusion: Place the silicon wafer completed in the previous step into a boron diffusion furnace. Use boron trichloride gas and oxygen with a volume ratio of 1:3 to deposit a boron source at 800°C. Then, heat at 920°C for 20 minutes to form a P-type doped polysilicon layer. The sheet resistance after diffusion is 100Ω / sq~120Ω / sq.

[0365] Laser film opening 1: Retain the borosilicate glass generated by the boron diffusion process, use a laser to locally groove the P-type doped polysilicon layer on the back of the substrate obtained in the previous step, and remove the P-type doped polysilicon layer in areas 362 and 352.

[0366] Alkali polishing: the remaining P-type doped polysilicon layer and laser damage in the grooved area in the previous step are etched away to form a back surface field region 352; the ungrooved and unetched area is the emitter region 351.

[0367] Deposition of intrinsic amorphous silicon 2: Using a tubular LPCVD device, a second tunneling oxide layer, a silicon oxide layer, and an intrinsic amorphous silicon layer are deposited on the back of the silicon wafer at 610°C.

[0368] Phosphorus diffusion: A tubular diffusion furnace is used to diffuse phosphorus into the silicon wafer. The gas atmosphere is nitrogen, oxygen, and vaporized phosphorus oxychloride. The nitrogen is 6 SLM, the oxygen is 6 SLM, and the phosphorus oxychloride is 1000 sccm. The temperature is 850°C to 950°C and the time is 100 minutes. The intrinsic amorphous silicon film deposited in the previous step is doped with phosphorus to form a phosphorus-doped polysilicon layer 352.

[0369] Laser film opening 2: Use a laser to locally groove the N-type doped polysilicon layer on the back side of the substrate obtained in the previous step, and remove the N-type doped polysilicon on the P-type doped polysilicon layers 351 and 362. The P-type doped polysilicon layer 351 is protected by the borosilicate glass layer and is therefore not removed by the laser.

[0370] Texturing: A chain HF machine is used to remove the phosphosilicate glass and borosilicate glass on the front side of the silicon wafer using a 5% by volume hydrofluoric acid solution. The wafer is then transferred to a tank texturing machine via a robot. The remaining phosphosilicate glass and borosilicate glass formed by boron diffusion and phosphorus diffusion, respectively, on the back side are retained as a back mask. The front side of the substrate 31 is texturing treated with a texturing solution to form an anti-reflective suede surface.

[0371] Deposition of dielectric layer: First, a tubular ALD device is used to deposit the dielectric layer on both sides. The process temperature is 270°C, and the gas flow rate is controlled at 50 sccm. First, the aluminum oxide layer is deposited, and then the aluminum oxynitride layer is deposited. Specifically, it includes:

[0372] ① Deposition of aluminum oxide layer: First, introduce Al(CH3)3 gas for 10 seconds, evacuate for 10 seconds, then introduce H2O gas for 10 seconds, and evacuate for 10 seconds. After the above two gases are introduced and evacuated in sequence, it is considered a growth cycle. The above cycle is repeated 5 times in total to deposit a 2nm thick aluminum oxide layer.

[0373] ② Deposition of aluminum oxynitride layer: The number of growth cycles with aluminum and oxygen sources was maintained at 15: During one growth cycle, Al(CH3)3 gas was introduced for 10 seconds, the atmosphere was evacuated for 10 seconds, then H2O gas was introduced for 10 seconds, and the atmosphere was evacuated for 10 seconds. The number of growth cycles with aluminum, oxygen, and nitrogen sources was maintained at 15: During one growth cycle, Al(CH3)3 gas was introduced for 10 seconds, the atmosphere was evacuated for 10 seconds, then H2O gas was introduced for 10 seconds, and the atmosphere was evacuated for 10 seconds, and finally NH3 gas was introduced for 20 seconds, and the atmosphere was evacuated for 10 seconds. Thus, a total of 30 growth cycles were performed to deposit a 4 nm thick aluminum oxynitride layer.

[0374] Deposition of the protective layer: The silicon wafer is transported to another tubular PECVD system, where a protective layer composed of silicon nitride and silicon oxynitride is deposited on the front side of the wafer. The wafer is first loaded into a graphite boat, with the back side of the wafer against the boat and the front side facing outward. The temperature inside the reactor tube is then raised to 550°C and held in a nitrogen atmosphere for 15 minutes. The pressure is then reduced to 2000 mTorr, where the silicon nitride and silicon oxynitride layers are deposited. The total coating process takes 50 minutes, resulting in a total protective layer thickness of 74nm and a 5% hydrogen content. The combined thickness of the dielectric and protective layers is 80nm.

[0375] Deposition of the second protective layer: PECVD is used to deposit a silicon nitride layer with a thickness of 80nm on the back of the silicon wafer.

[0376] Screen printing: Printing silver paste on the back side at a sintering process temperature of 840°C to complete the preparation of the fifth electrode, printing silver paste on the back side at a sintering process temperature of 840°C to complete the production of the sixth electrode; at a process temperature of 300°C, complete the light injection into the passivated contact solar cell.

[0377] Example 10

[0378] 6 , Example 7 also provides an N-type IBC solar cell 300 . The dielectric layer 36 of the N-type IBC solar cell 300 is an aluminum oxynitride layer. Similarly, in the method for preparing the N-type IBC solar cell 300 , the aluminum oxynitride layer is deposited by ALD, and the rest of the method remains the same as Example 9.

[0379] Comparative Example 1

[0380] Comparative Example 1 provides a back-side passivated solar cell, wherein the dielectric layer of the back-side passivated solar cell is an aluminum oxide layer. In the preparation method of the back-side passivated solar cell, the aluminum oxide layer is deposited by ALD, and the rest is consistent with Example 1.

[0381] Comparative Example 2

[0382] Comparative Example 2 provides a passivated contact solar cell, wherein the dielectric layer of the passivated contact solar cell is an aluminum oxide layer. In the preparation method of the passivated contact solar cell, the aluminum oxide layer is deposited by ALD, and the rest is consistent with Example 3.

[0383] Comparative Example 3

[0384] Comparative Example 3 provides a back-passivated solar cell, which differs from Example 1 in that, in the step of preparing the aluminum oxynitride layer in Example 6, the aluminum source, oxygen source, and nitrogen source are introduced simultaneously five times.

[0385] Comparative Example 4

[0386] Comparative Example 4 provides a back-passivated solar cell, which differs from Example 1 in that, in the step of preparing the aluminum oxynitride layer in Example 6, the aluminum source, oxygen source, and nitrogen source are introduced simultaneously 9 times.

[0387] Comparative Example 5

[0388] Comparative Example 5 provides a P-type IBC solar cell, the dielectric layer of which is an aluminum oxide layer. In the preparation method of the passivated contact solar cell, the aluminum oxide layer is deposited by ALD, and the rest is consistent with Example 7.

[0389] Comparative Example 6

[0390] Comparative Example 6 provides an N-type IBC solar cell, wherein the dielectric layer of the N-type IBC solar cell is an aluminum oxide layer. In the preparation method of the passivated contact solar cell, the aluminum oxide layer is deposited by ALD, and the rest is consistent with Example 7.

[0391] Testing and data analysis

[0392] Dielectric layer samples of Examples 1, 5, and 6, as well as Comparative Examples 3 and 4, were analyzed using a SIMS (Second Ion Mass Spectroscopy) instrument. A primary ion beam was continuously bombarded on the sample surface, causing sputtering of the atomic layer on the sample surface. Positive ions, negative ions, neutral particles, and photons were sputtered out. Elemental analysis was performed by collecting charged particles with a specific charge-to-mass ratio. The analysis results are as follows:

[0393] Table 1 Elemental analysis of the dielectric layer of the solar cells of Examples 1, 5, 6 and Comparative Examples 3 and 4:

[0394] As can be seen from Table 1, in Comparative Examples 3 and 4, the number of times n the nitrogen source is provided during the cyclic growth is less than 10, which cannot satisfy the requirement that the nitrogen content reaches 4 wt% and the hydrogen content reaches 4 wt%. As a result, the photoelectric conversion efficiency of Comparative Examples 3 and 4 is lower than that of Examples 1, 5 and 6.

[0395] The performance of the solar cells of Examples 1 to 4 and Comparative Examples 1 and 2 was tested respectively. The electrical performance of the cells was tested using a Halm tester. The results are as follows:

[0396] Table 2 Cell performance of back-passivated solar cells of Example 1, Example 2 and Comparative Example 1:

[0397] Table 3 Performance of passivated contact solar cells of Example 3, Example 4 and Comparative Example 2:

[0398] Table 4 Performance of P-type back contact solar cells of Example 7, Example 8 and Comparative Example 5:

[0399] Table 5 Performance of N-type back contact solar cells of Example 9, Example 10 and Comparative Example 6:

[0400] From the data results of Example 1 and Comparative Example 1 in Table 2, Example 3 and Comparative Example 2 in Table 3, Example 7 and Comparative Example 5 in Table 4, and Example 9 and Comparative Example 6 in Table 5, it can be seen that after using a composite dielectric layer of an aluminum oxynitride layer and an aluminum oxide layer to replace the aluminum oxide layer, the photoelectric conversion efficiency is better. Because the passivation quality of the composite dielectric layer is better, the open-circuit voltage of the solar cell using the composite dielectric layer is higher; at the same time, the composite dielectric layer has a higher refractive index, so the solar cell has better current performance. Through the above synergistic effect, the photoelectric conversion efficiency of the solar cell is improved to a certain extent.

[0401] Examples 2, 4, 8, and 10 all use a single aluminum oxynitride layer as the dielectric layer. Compared to the composite dielectric layers of aluminum oxynitride and aluminum oxide in Examples 1, 3, 7, and 9, the two solutions achieve similar photoelectric conversion efficiencies. The composite dielectric layer offers superior passivation quality, resulting in higher open-circuit voltages for solar cells using the composite thin film. However, the refractive index of a single aluminum oxynitride layer is higher, resulting in better current performance for solar cells using the single layer.

[0402] In summary, the present application can cooperate with each other to support the increase of the charge amount of the dielectric layer, the improvement of the interface continuity of the dielectric layer, and the reduction of the interface defect density to improve the passivation quality by selecting a specific dielectric layer material and controlling its element content. In addition, it can effectively increase the refractive index and increase the absorption of incident light, thereby comprehensively improving the photoelectric conversion efficiency of the solar cell. Among them, the dielectric layer includes aluminum oxynitride, which has a high density of negative charges and can reduce the loss of short-circuit current density. In addition, the high density of negative charges can achieve field passivation, reduce the concentration of carriers near the interface of the solar cell, and thus reduce the recombination of carriers. Aluminum oxynitride has good growth properties, can reduce interface roughness, improve interface continuity, and reduce the distribution of dangling bonds. By regulating the element content of the dielectric layer, the nitrogen content of the dielectric layer is higher than 4wt%. After nitrogen and hydrogen form bonds, more hydrogen elements can be introduced, so that the hydrogen element content is maintained above 4wt%, providing sufficient hydrogen atoms to achieve chemical passivation, saturate the dangling bonds between the interfaces, reduce defect recombination centers, and reduce interface defect density. The increase in nitrogen content increases the density of the dielectric layer and the refractive index, which can improve the anti-reflection effect of the solar cell and increase the absorption of incident light.

[0403] The above is a detailed introduction to a dielectric layer and preparation method, solar cell, and photovoltaic module disclosed in the embodiments of the present application. Specific examples are used herein to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the dielectric layer and preparation method, solar cell, photovoltaic module and its core idea of ​​the present application: At the same time, for general technical personnel in this field, based on the ideas of the present application, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as a limitation on the present application.

[0404] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0405] The above-described embodiments merely represent several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that a person of ordinary skill in the art may make various modifications and improvements without departing from the spirit of the present application, and these modifications and improvements fall within the scope of protection of the present application. Therefore, the scope of protection of the present patent application shall be determined by the appended claims.

Claims

1. A dielectric layer, characterized in that: Used in solar cells, the dielectric layer comprises an aluminum nitride oxide layer containing hydrogen, the nitrogen content of the dielectric layer is higher than 4wt% and the hydrogen content is higher than 4wt%.

2. The dielectric layer according to claim 1, characterized in that The dielectric layer includes an aluminum oxynitride layer.

3. The dielectric layer according to claim 1 or 2, characterized in that: The dielectric layer includes a first dielectric layer and a second dielectric layer which are stacked.

4. The dielectric layer according to any one of claims 1 to 3, characterized in that: The first dielectric layer includes an aluminum oxynitride layer.

5. The dielectric layer according to any one of claims 1 to 4, characterized in that: The second dielectric layer includes any one of an aluminum oxide layer, a gallium oxide layer, a titanium dioxide layer, a zirconium dioxide layer, and a tantalum pentoxide layer.

6. The dielectric layer according to any one of claims 3 to 5, characterized in that: The growth substrate of the second dielectric layer is a P-type substrate or an N-type substrate, and the first dielectric layer is arranged on a surface of the second dielectric layer away from the P-type substrate or the N-type substrate.

7. The dielectric layer according to any one of claims 3 to 6, characterized in that: The second dielectric layer includes an aluminum oxide layer.

8. The dielectric layer according to any one of claims 3 to 7, characterized in that: The thickness of the second dielectric layer is less than or equal to the thickness of the first dielectric layer.

9. The dielectric layer according to any one of claims 1 to 8, characterized in that: The thickness of the dielectric layer is less than 30 nm.

10. The dielectric layer according to any one of claims 1 to 9, characterized in that: The refractive index of the dielectric layer is in the range of about 1.65 to 2.

10.

11. The dielectric layer according to any one of claims 1 to 10, characterized in that: The roughness of the dielectric layer is in the range of about 0.15 nm to 0.3 nm.

12. The dielectric layer according to any one of claims 6 to 11, characterized in that: The P-type substrate includes any one of a P-type silicon wafer, a P-type epitaxial growth doping layer and a P-type diffusion layer.

13. The dielectric layer according to any one of claims 6 to 12, characterized in that: The N-type substrate includes an N-type silicon wafer.

14. A method for preparing a dielectric layer, characterized in that: The dielectric layer is a dielectric layer according to any one of claims 1 to 13, and the preparation method comprises the following steps: Chemical adsorption: sequentially providing an aluminum source and an oxygen source to perform chemical adsorption on the surface of the P-type substrate or the N-type substrate to complete a growth, cyclically growing x times to deposit the dielectric layer, and providing a nitrogen source at least 10 times in the x-cycle growth to make the nitrogen content of the dielectric layer higher than 4wt% and the hydrogen content higher than 4wt%; Standing: the dielectric layer is stood in an inert atmosphere at a temperature greater than or equal to 520° C. for a standing time of 10 min to 40 min.

15. The preparation method according to claim 14, characterized in that: The dielectric layer comprises a first dielectric layer and a second dielectric layer, and the chemical adsorption step comprises: sequentially providing the aluminum source and the oxygen source, performing chemical adsorption on the surface of the P-type substrate or the N-type substrate to complete a growth, and performing cyclic growth y times to deposit the second dielectric layer, where y is greater than 0; The aluminum source and the oxygen source are provided in sequence, chemical adsorption is performed on the surface of the second dielectric layer facing away from the P-type substrate or the N-type substrate to complete a growth, the first dielectric layer is deposited for z cycles of growth, and a nitrogen source is provided for at least 10 of the z cycles of growth.

16. The preparation method according to claim 15, characterized in that: The step of standing comprises: standing the first dielectric layer and the second dielectric layer in an inert atmosphere, the standing temperature is about 520° C. to 600° C., and the standing time is about 10 min to 40 min.

17. The preparation method according to claim 15 or 16, characterized in that: y is less than or equal to z.

18. The preparation method according to any one of claims 15 to 17, characterized in that: In the step of depositing the second dielectric layer, a growth temperature is about 250° C. to 400° C.

19. The preparation method according to any one of claims 15 to 18, characterized in that: In the step of depositing the first dielectric layer, a growth temperature is about 250° C. to 400° C.

20. The preparation method according to any one of claims 14 to 19, characterized in that: The gas flow rates of the aluminum source, the oxygen source, and the nitrogen source are approximately 20 sccm to 100 sccm.

21. The preparation method according to any one of claims 14 to 20, characterized in that: The aluminum source is provided for about 8s to 12s, the oxygen source is provided for about 8s to 12s, and the nitrogen source is provided for about 15s to 25s.

22. The preparation method according to any one of claims 14 to 21, characterized in that: The aluminum source includes a mixture of one or more of Al(CH3)3, AlCl3, Al(CH3)2Cl and (CH3)2(C2H5)N:AlH3.

23. The preparation method according to any one of claims 14 to 22, characterized in that: The oxygen source includes a mixture of one or more of H2O, O2, O3, N2O and CO2.

24. The preparation method according to any one of claims 14 to 23, characterized in that: The nitrogen source includes a mixture of one or more of N2O and NH3.

25. A solar cell, characterized in that: The solar cell comprises a dielectric layer as described in any one of claims 1-13, wherein the dielectric layer is disposed on a surface of the P-type substrate or the N-type substrate, and the solar cell further comprises a protective layer stacked on a surface of the dielectric layer away from the P-type substrate or the N-type substrate.

26. The solar cell according to claim 25, characterized in that: The thickness of the protective layer is greater than or equal to 50 nm.

27. The solar cell according to claim 25 or 26, characterized in that: The sum of the thicknesses of the dielectric layer and the protective layer is approximately 75 nm to 85 nm.

28. The solar cell according to any one of claims 25 to 27, characterized in that: The equivalent refractive index of the dielectric layer and the protective layer is about 1.85-2.

20.

29. The solar cell according to any one of claims 25 to 28, characterized in that: The material of the protective layer includes one or more of silicon nitride, silicon oxynitride, silicon oxide and silicon carbide, and the hydrogen content of the protective layer is greater than or equal to 1wt%.

30. The solar cell according to any one of claims 25 to 29, characterized in that: The solar cell includes any one of a back-passivated solar cell, a passivated contact solar cell, an N-type back-contact solar cell and a P-type back-contact solar cell.

31. The solar cell according to any one of claims 25 to 30, characterized in that: The solar cell is a back-passivated solar cell, and the solar cell comprises: A first P-type silicon wafer, wherein the first P-type silicon wafer has a first surface and a second surface disposed opposite to each other, and the first surface is a light incident surface; An N-type diffusion layer, the N-type diffusion layer is disposed on the first surface; A first passivation layer, the first passivation layer being disposed on a side of the N-type diffusion layer away from the first P-type silicon wafer; A first protective layer, the first protective layer being disposed on a side of the first passivation layer away from the first P-type silicon wafer; a dielectric layer, the dielectric layer being an aluminum oxynitride layer, and the dielectric layer being disposed on the second surface; a second protective layer, the second protective layer being disposed on a side of the aluminum oxynitride layer facing away from the first P-type silicon wafer; and The first electrode structure includes a first electrode and a second electrode, the first electrode is in ohmic contact with the first P-type silicon wafer, and the second electrode is in ohmic contact with the N-type diffusion layer.

32. The solar cell according to any one of claims 25 to 30, characterized in that: The solar cell is a back-passivated solar cell, and the solar cell comprises: A first P-type silicon wafer, wherein the first P-type silicon wafer has a first surface and a second surface disposed opposite to each other, and the first surface is a light incident surface; An N-type diffusion layer, the N-type diffusion layer is disposed on the first surface; A first passivation layer, the first passivation layer being disposed on a side of the N-type diffusion layer away from the first P-type silicon wafer; A first protective layer, the first protective layer being disposed on a side of the first passivation layer away from the first P-type silicon wafer; a dielectric layer, the dielectric layer comprising an aluminum oxide layer and an aluminum oxynitride layer stacked in sequence; the aluminum oxide layer is disposed on the second surface; a second protective layer, the second protective layer being disposed on a side of the aluminum oxynitride layer facing away from the first P-type silicon wafer; and The first electrode structure includes a first electrode and a second electrode, the first electrode is in ohmic contact with the first P-type silicon wafer, and the second electrode is in ohmic contact with the N-type diffusion layer.

33. The solar cell according to any one of claims 25 to 30, characterized in that: The solar cell is a passivated contact solar cell, and the solar cell comprises: A first N-type silicon wafer, wherein the first N-type silicon wafer has a third surface and a fourth surface opposite to the third surface, and the third surface is a light incident surface; A P-type diffusion layer, the P-type diffusion layer is disposed on the third surface; a dielectric layer, wherein the dielectric layer is an aluminum oxynitride layer, and the aluminum oxynitride layer is disposed on a side of the P-type diffusion layer away from the first N-type silicon wafer; a third protective layer, the third protective layer being disposed on a side of the aluminum oxynitride layer facing away from the first N-type silicon wafer; A first tunneling oxide layer, wherein the first tunneling oxide layer is disposed on the fourth surface; A first doped polysilicon layer, wherein the first doped polysilicon layer is disposed on a side of the first tunneling oxide layer away from the first N-type silicon wafer; a first anti-reflection layer, the first anti-reflection layer being disposed on a side of the first doped polysilicon layer facing away from the first N-type silicon wafer; and The second electrode structure includes a third electrode and a fourth electrode, the third electrode is in ohmic contact with the P-type diffusion layer, and the fourth electrode is in ohmic contact with the first doped polysilicon layer.

34. The solar cell according to any one of claims 25 to 30, characterized in that: The solar cell is a passivated contact solar cell, and the solar cell comprises: A first N-type silicon wafer, wherein the first N-type silicon wafer has a third surface and a fourth surface opposite to the third surface, and the third surface is a light incident surface; A P-type diffusion layer, the P-type diffusion layer is disposed on the third surface; A dielectric layer, the dielectric layer comprising an aluminum oxide layer and an aluminum oxynitride layer stacked in sequence; the aluminum oxide layer is disposed on a side of the P-type diffusion layer away from the first N-type silicon wafer; a third protective layer, the third protective layer being disposed on a side of the aluminum oxynitride layer facing away from the first N-type silicon wafer; A first tunneling oxide layer, wherein the first tunneling oxide layer is disposed on the fourth surface; A first doped polysilicon layer, wherein the first doped polysilicon layer is disposed on a side of the first tunneling oxide layer away from the first N-type silicon wafer; a first anti-reflection layer, the first anti-reflection layer being disposed on a side of the first doped polysilicon layer facing away from the first N-type silicon wafer; and The second electrode structure includes a third electrode and a fourth electrode, the third electrode is in ohmic contact with the P-type diffusion layer, and the fourth electrode is in ohmic contact with the first doped polysilicon layer.

35. The solar cell according to any one of claims 25 to 30, characterized in that: The solar cell is an N-type back-contact solar cell, and the solar cell further comprises: a second N-type silicon wafer, wherein the second N-type silicon wafer has a fifth surface and a sixth surface opposite to the fifth surface, and the fifth surface is a light incident surface; a second passivation layer, wherein the second passivation layer is disposed on the fifth surface; a fourth protective layer, the fourth protective layer being disposed on a side of the second passivation layer away from the second N-type silicon wafer; a second tunneling oxide layer, the second tunneling oxide layer comprising a first portion and a second portion, the first portion and the second portion being disposed on the sixth surface; a second doped polysilicon layer, wherein the second doped polysilicon layer comprises a P-type doped polysilicon layer and an N-type doped polysilicon layer, wherein the P-type doped polysilicon layer is disposed on a side of the first portion away from the second N-type silicon wafer, and the N-type doped polysilicon layer is disposed on a side of the second portion away from the second N-type silicon wafer; a dielectric layer, the dielectric layer being an aluminum oxynitride layer, the dielectric layer comprising a third portion, a fourth portion and a fifth portion, the third portion being disposed on a side of the P-type doped polysilicon layer away from the second N-type silicon wafer, the fourth portion being disposed on the sixth side and between the P-type doped polysilicon layer and the N-type doped polysilicon layer, and the fifth portion being disposed on a side of the N-type doped polysilicon layer away from the second N-type silicon wafer; a fifth protective layer, the fifth protective layer being disposed on the third portion, the fourth portion, and a side of the fifth portion away from the second N-type silicon wafer; and The third electrode structure includes a fifth electrode and a sixth electrode, wherein the fifth electrode is in ohmic contact with the P-type doped polysilicon layer, and the sixth electrode is in ohmic contact with the N-type doped polysilicon layer.

36. The solar cell according to any one of claims 25 to 30, characterized in that: The solar cell is an N-type back-contact solar cell, and the solar cell comprises: a second N-type silicon wafer, wherein the second N-type silicon wafer has a fifth surface and a sixth surface opposite to the fifth surface, and the fifth surface is a light incident surface; a second passivation layer, wherein the second passivation layer is disposed on the fifth surface; a fourth protective layer, the fourth protective layer being disposed on a side of the second passivation layer away from the second N-type silicon wafer; a second tunneling oxide layer, the second tunneling oxide layer comprising a first portion and a second portion, the first portion and the second portion being disposed on the sixth surface; a second doped polysilicon layer, wherein the second doped polysilicon layer comprises a P-type doped polysilicon layer and an N-type doped polysilicon layer, wherein the P-type doped polysilicon layer is disposed on a side of the first portion away from the second N-type silicon wafer, and the N-type doped polysilicon layer is disposed on a side of the second portion away from the second N-type silicon wafer; a dielectric layer, the dielectric layer comprising a third portion, a fourth portion, and a fifth portion; The third part includes a first aluminum oxide layer and a first aluminum oxynitride layer stacked in sequence, wherein the first aluminum oxide layer is disposed on a side of the P-type doped polysilicon layer away from the second N-type silicon wafer; The fourth portion includes a second aluminum oxide layer and a second aluminum oxynitride layer stacked in sequence, wherein the second aluminum oxide layer is disposed on the sixth surface and between the P-type doped polysilicon layer and the N-type doped polysilicon layer; The fifth portion includes a third aluminum oxide layer and a third aluminum oxynitride layer stacked in sequence, wherein the third aluminum oxide layer is disposed on a side of the N-type doped polysilicon layer away from the second N-type silicon wafer; and a fifth protective layer, the fifth protective layer being disposed on a side of the first aluminum oxynitride layer, the second aluminum oxynitride layer, and the third aluminum oxynitride layer away from the second N-type silicon wafer; and The third electrode structure includes a fifth electrode and a sixth electrode, wherein the fifth electrode is in ohmic contact with the P-type doped polysilicon layer, and the sixth electrode is in ohmic contact with the N-type doped polysilicon layer.

37. The solar cell according to any one of claims 25 to 30, characterized in that: The solar cell is a P-type back-contact solar cell, and the solar cell comprises: a second P-type silicon wafer, wherein the second P-type silicon wafer has a seventh surface and an eighth surface opposite to the seventh surface, and the seventh surface is a light incident surface; a third passivation layer, the third passivation layer being disposed on the seventh surface; a sixth protective layer, the sixth protective layer being disposed on a side of the third passivation layer away from the second P-type silicon wafer; a third tunneling oxide layer, wherein the third tunneling oxide layer is disposed on the eighth surface; An N-type doped polysilicon layer, wherein the N-type doped polysilicon layer is disposed on a side of the third tunneling oxide layer away from the second P-type silicon wafer; a dielectric layer, the dielectric layer being an aluminum oxynitride layer, the dielectric layer comprising a sixth portion and a seventh portion, the sixth portion being disposed on the eighth surface, and the seventh portion being disposed on a surface of the N-type doped polysilicon layer away from the second P-type silicon wafer; a seventh protective layer, the seventh protective layer being disposed on a side of the sixth portion and the seventh portion away from the second N-type silicon wafer; and A fourth electrode structure includes a seventh electrode and an eighth electrode, wherein the seventh electrode is in ohmic contact with the second P-type silicon wafer, and the eighth electrode is in ohmic contact with the N-type doped polysilicon layer.

38. The solar cell according to any one of claims 25 to 30, characterized in that: The solar cell is a P-type back-contact solar cell, and the solar cell comprises: a second P-type silicon wafer, wherein the second P-type silicon wafer has a seventh surface and an eighth surface opposite to the seventh surface, and the seventh surface is a light incident surface; a third passivation layer, the third passivation layer being disposed on the seventh surface; a sixth protective layer, the sixth protective layer being disposed on a side of the third passivation layer away from the second P-type silicon wafer; a third tunneling oxide layer, wherein the third tunneling oxide layer is disposed on the eighth surface; An N-type doped polysilicon layer, wherein the N-type doped polysilicon layer is disposed on a side of the third tunneling oxide layer away from the second P-type silicon wafer; a dielectric layer, the dielectric layer comprising a sixth portion and a seventh portion; The sixth portion includes a fourth aluminum oxide layer and a fourth aluminum oxynitride layer stacked in sequence, and the fourth aluminum oxide layer is disposed on the eighth surface; The seventh portion includes a fifth aluminum oxide layer and a fifth aluminum oxynitride layer stacked in sequence, wherein the fifth aluminum oxide layer is disposed on a side of the N-type doped polysilicon layer away from the second P-type silicon wafer; A seventh protective layer, the seventh protective layer is arranged on the fourth aluminum nitride oxide layer and the fifth aluminum nitride oxide layer away from the second N-type one side of the silicon wafer; and A fourth electrode structure includes a seventh electrode and an eighth electrode, wherein the seventh electrode is in ohmic contact with the second P-type silicon wafer, and the eighth electrode is in ohmic contact with the N-type doped polysilicon layer.

39. A photovoltaic module, characterized in that: The photovoltaic module comprises the solar cell according to any one of claims 25-38.

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