Solar cell and preparation method thereof

Abstract

The invention relates to the field of solar cells, particularly provides a solar cell and a preparation method, and aims to solve the problem that an ultrathin silicon oxide layer with uniform thickness is difficult to form on a substrate at present. In order to achieve the purpose, the preparation method of the solar cell comprises the steps of providing a substrate; forming a first hydrogenated intrinsic amorphous silicon layer on the whole first surface of the substrate; the substrate is placed in a mixed solution of H2O2 and HF, the concentration of H2O2 is larger than that of HF, the first hydrogenated intrinsic amorphous silicon layer is oxidized and corroded to form a first amorphous silicon oxide layer located on the first surface of the substrate, and the thickness of the first amorphous silicon oxide layer ranges from 0.4 nm to 1.5 nm. The first amorphous silicon oxide layer is formed by gradually thinning the first hydrogenated intrinsic amorphous silicon layer which is thicker while being oxidized and corroded, and the thickness of the obtained ultrathin first amorphous silicon oxide layer is more uniform.

Description

Technical Field

[0001] The present disclosure relates to the field of solar cells, and specifically provides a solar cell and a preparation method thereof. Background Art

[0002] With the development of solar cells, the technology of solar cells has been continuously updated and developed, such as PERC cells, passivated contact cells (TOPCON cells), heterojunction (Heterojunction Technology, HJT) cells, and back contact cells.

[0003] The HJT cell includes a substrate, a first surface of the substrate is provided with a first hydrogenated intrinsic amorphous silicon layer, a first doped amorphous silicon layer and a first conductive layer in sequence, and a second surface of the substrate is provided with a second hydrogenated intrinsic amorphous silicon layer, a second doped amorphous silicon layer and a second conductive layer in sequence. The first hydrogenated intrinsic amorphous silicon layer and the second hydrogenated intrinsic amorphous silicon layer are mainly used to prevent epitaxial growth of the substrate on the first surface and the second surface. Once epitaxial growth occurs on the first surface and the second surface of the substrate, the interface passivation will be deteriorated, affecting the efficiency of the HJT cell.

[0004] However, the structure of the hydrogenated intrinsic amorphous silicon layer is porous and loose, with poor density, many internal defects and low electrical conductivity. At present, the industry is trying to use an ultra-thin silicon oxide layer to replace the hydrogenated intrinsic amorphous silicon layer. Due to the high density of the silicon oxide layer, only a very thin silicon oxide layer is needed to prevent the epitaxial growth of the substrate, which helps to reduce the series resistance of the HJT battery. In addition, the silicon oxide layer has a high density and is not easily invaded by water vapor, which helps to improve the reliability of the HJT battery. However, the current preparation process makes it difficult to form an ultra-thin silicon oxide layer with uniform thickness on the substrate.

[0005] Therefore, there is an urgent need for a solar cell and a preparation method that can solve the current problem of difficulty in forming an ultra-thin silicon oxide layer with uniform thickness on a substrate. Summary of the invention

[0006] The present disclosure aims to solve the problem that it is currently difficult to form an ultra-thin silicon oxide layer with uniform thickness on a substrate, and provides a solar cell and a preparation method thereof.

[0007] In a first aspect, the present disclosure provides a method for preparing a solar cell, comprising: providing a substrate, the substrate having a first surface and a second surface opposite to the first surface; forming a first hydrogenated intrinsic amorphous silicon layer on the entire surface of the first surface of the substrate; placing the substrate in a mixed solution of H2O2 and HF, wherein the concentration of H2O2 is greater than the concentration of HF, oxidizing and corroding the first hydrogenated intrinsic amorphous silicon layer to form a first amorphous silicon oxide layer located on the first surface of the substrate, wherein the thickness of the first amorphous silicon oxide layer is 0.4 nm to 1.5 nm.

[0008] In some exemplary embodiments, the preparation method further includes: forming a second hydrogenated intrinsic amorphous silicon layer on the second surface of the substrate; and oxidizing and corroding the second hydrogenated intrinsic amorphous silicon layer while placing the substrate in a mixed solution of H2O2 and HF to form a second amorphous silicon oxide layer located on the second surface of the substrate, wherein the thickness of the second amorphous silicon oxide layer is 0.4 nm to 1.5 nm.

[0009] In some exemplary embodiments, the molar ratio of H2O2 to HF is (4-6):1.

[0010] In some exemplary embodiments, the preparation method also includes: forming a first doped layer, a first conductive layer, and a first electrode on a side of the first amorphous silicon oxide layer away from the substrate; and sequentially forming a second doped layer, a second conductive layer, and a second electrode on a side of the second amorphous silicon oxide layer away from the substrate, the doping type of the second doped layer being opposite to the doping type of the first doped layer.

[0011] In some exemplary embodiments, the preparation method further includes: forming a first doped layer on a side of the first amorphous silicon oxide layer away from the substrate, and sequentially forming a first conductive layer and a first electrode on a side of the first doped layer away from the substrate; forming a second doped layer on a side of the first amorphous silicon oxide layer away from the substrate, the doping type of the second doped layer is opposite to the doping type of the first doped layer, and the first doped layer and the second doped layer are arranged side by side in a first direction and are insulated from each other; and sequentially forming a second conductive layer and a second electrode on a side of the second doped layer away from the substrate.

[0012] In some exemplary embodiments, the thickness of the first hydrogenated intrinsic amorphous silicon layer and the second hydrogenated intrinsic amorphous silicon layer is 5 nm to 20 nm, and the reaction time of placing the substrate in the mixed solution of H2O2 and HF is 25 s to 35 s.

[0013] In some exemplary embodiments, the preparation method further includes: before forming the first doping layer, forming a third hydrogenated intrinsic amorphous silicon layer on a side of the first amorphous silicon oxide layer away from the substrate.

[0014] In some exemplary embodiments, the preparation method further includes: before forming the second doping layer, forming a fourth hydrogenated intrinsic amorphous silicon layer on a side of the second amorphous silicon oxide layer away from the substrate.

[0015] In some exemplary embodiments, the material of the first doping layer is hydrogenated amorphous silicon, hydrogenated microcrystalline silicon or hydrogenated oxygen-doped microcrystalline silicon; and / or the material of the second doping layer is hydrogenated amorphous silicon, hydrogenated microcrystalline silicon or hydrogenated oxygen-doped microcrystalline silicon, hydrogenated microcrystalline silicon carbide or hydrogenated carbon-doped microcrystalline silicon oxide.

[0016] In a second aspect, the present disclosure provides a solar cell prepared by the above-mentioned preparation method, comprising: a substrate having a first surface and a second surface opposite to the first surface; a first amorphous silicon oxide layer, which is arranged on the entire surface and located on the first surface of the substrate, and has a thickness of 0.4nm to 1.5nm.

[0017] In some exemplary embodiments, the solar cell further includes: a first doped layer located on a side of the first amorphous silicon oxide layer away from the substrate; a first conductive layer located on a side of the first doped layer away from the substrate; a first electrode electrically connected to the first conductive layer; a second amorphous silicon oxide layer located on the second surface of the substrate and having a thickness of 0.4 nm to 1.5 nm; a second doped layer located on a side of the second amorphous silicon oxide layer away from the substrate; a second conductive layer located on a side of the second doped layer away from the substrate; and a second electrode electrically connected to the second conductive layer.

[0018] In some exemplary embodiments, the solar cell further includes: a first doped layer located on a side of the first amorphous silicon oxide layer away from the substrate; a first conductive layer located on a side of the first doped layer away from the substrate; a first electrode electrically connected to the first conductive layer; a second doped layer located on a side of the first amorphous silicon oxide layer away from the substrate, arranged parallel to the first doped layer in a first direction and insulated from each other; a second conductive layer located on a side of the second doped layer away from the substrate; and a second electrode electrically connected to the second conductive layer.

[0019] In some exemplary embodiments, a third hydrogenated intrinsic amorphous silicon layer is disposed between the first amorphous silicon oxide layer and the first doping layer.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] The present disclosure provides a method for preparing a solar cell, comprising: providing a substrate, the substrate having a first surface and a second surface opposite to the first surface; forming a first hydrogenated intrinsic amorphous silicon layer on the entire surface of the first surface of the substrate; placing the substrate in a mixed solution of H2O2 and HF, wherein the concentration of H2O2 is greater than the concentration of HF, oxidizing and corroding the first hydrogenated intrinsic amorphous silicon layer to form a first amorphous silicon oxide layer located on the first surface of the substrate, the thickness of the first amorphous silicon oxide layer being 0.4nm to 1.5nm; forming a first doping layer on a side of the first amorphous silicon oxide layer away from the substrate; and sequentially forming a first conductive layer and a first electrode on a side of the first doping layer away from the substrate. The first amorphous silicon oxide layer is formed by gradually thinning the first hydrogenated intrinsic amorphous silicon layer by oxidation and corrosion while the thickness of the obtained ultra-thin first amorphous silicon oxide layer is relatively uniform. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The preferred embodiments of the present disclosure are described below in conjunction with the accompanying drawings, in which:

[0023] Figure 1 It is a cross-sectional structural diagram of a heterojunction battery in the known technology;

[0024] Figure 2 is a flow chart of a method for preparing a solar cell provided by at least one embodiment of the present disclosure;

[0025] FIG. 3A to FIG. 3B is a cross-sectional view of a solar cell during the preparation process provided by at least one embodiment of the present disclosure;

[0026] Figure 3C is a cross-sectional view of a solar cell provided by at least one embodiment of the present disclosure;

[0027] Figure 4A is a cross-sectional view of a solar cell during the preparation process provided by at least one embodiment of the present disclosure;

[0028] Figure 4B is another cross-sectional view of a solar cell provided in at least one embodiment of the present disclosure.

[0029] Description of reference numerals:

[0030] 1. substrate; 11. first surface; 12. second surface; 13. first doped region; 14. second doped region; 15. isolation region; 2. first amorphous silicon oxide layer; 2a. first hydrogenated intrinsic amorphous silicon layer; 3. third hydrogenated intrinsic amorphous silicon layer; 4. first doped layer; 5. second amorphous silicon oxide layer; 5a. second hydrogenated intrinsic amorphous silicon layer; 6. fourth hydrogenated intrinsic amorphous silicon layer; 7. second doped layer; 81. first conductive layer; 82. second conductive layer; 91. first electrode; 92. second electrode; 10. intrinsic passivation layer; 20. anti-reflection layer; X, first direction. DETAILED DESCRIPTION

[0031] The preferred embodiments of the present disclosure are described below with reference to the accompanying drawings. It should be understood by those skilled in the art that these embodiments are only used to explain the technical principles of the present disclosure and are not intended to limit the protection scope of the present disclosure.

[0032] It should be noted that in the description of the present disclosure, the terms "upper", "lower", "left", "right", "inner", "outer" and the like indicating directions or positional relationships are based on the directions or positional relationships shown in the drawings, which are only for the convenience of description, and do not indicate or imply that the device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present disclosure. In addition, the terms "first" and "second" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0033] In addition, it should be noted that in the description of the present disclosure, unless otherwise clearly specified and limited, the terms "installation", "setting", and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection, an indirect connection through an intermediate medium, or the internal connection of two elements. For those skilled in the art, the specific meanings of the above terms in the present disclosure can be understood according to specific circumstances.

[0034] The existing HJT cell includes a substrate 1′, a first surface 11′ of the substrate 1′ is sequentially provided with a first hydrogenated intrinsic amorphous silicon layer 3′, a first doped amorphous silicon layer 4′ and a first conductive layer 81′, and a second surface 12′ of the substrate 1′ is sequentially provided with a second hydrogenated intrinsic amorphous silicon layer 6′, a second doped amorphous silicon layer 7′ and a second conductive layer 82′. Among them, the first hydrogenated intrinsic amorphous silicon layer 3′ and the second hydrogenated intrinsic amorphous silicon layer 6′ are mainly used to prevent the substrate 1′ from epitaxially growing on the first surface 11′ and the second surface 12′. Once the substrate 1′ epitaxially grows on the first surface 11′ and the second surface 12′, the interface passivation will be deteriorated, affecting the efficiency of the HJT cell. Since the structure of the intrinsic amorphous silicon layer is porous and loose, the density is poor, and there are many internal defects, thicker intrinsic amorphous silicon is required to effectively prevent the substrate 1′ from epitaxially growing on the first surface 11′ and the second surface 12′, which also leads to a higher series resistance of the HJT cell.

[0035] For example, the thickness of the first hydrogenated intrinsic amorphous silicon layer 3' and the second hydrogenated intrinsic amorphous silicon layer 6' are both 10nm, the first doped layer 4' is P-type doped and has a thickness of 10nm, and the second doped layer 7' is N-type doped and has a thickness of 10nm. Its cell efficiency is 25.04%, the open circuit voltage is 748mV, the fill factor is 85.2%, and the short circuit current density is 39.3mA / cm2 .

[0036] Currently, the industry is trying to use an ultra-thin silicon oxide layer to replace the hydrogenated intrinsic amorphous silicon layer. Since the silicon oxide layer has a high density, only a very thin silicon oxide layer is needed to prevent the epitaxial growth of the substrate 1′, which helps to reduce the series resistance of the HJT battery. In addition, the silicon oxide layer has a high density and is not easily invaded by water vapor, which helps to improve the reliability of the HJT battery.

[0037] At present, the common method for preparing ultra-thin silicon oxide layers is to use chemical vapor deposition (such as PECVD, plasma enhanced chemical vapor deposition) or wet oxidation using H2O2 solution. As for the preparation of ultra-thin silicon oxide layers by PECVD, since the thickness of the required silicon oxide layer is too thin (generally below 1.5nm or 1nm), the uniformity of the film growth is poor and it is difficult to achieve the expected results. In the process of preparing ultra-thin silicon oxide layers by wet oxidation, since the silicon wafer itself is hydrophobic, it is also difficult to prepare an ultra-thin silicon oxide layer with relatively uniform thickness by wet oxidation. In summary, the current process control for preparing ultra-thin silicon oxide layers is difficult, the process stability is poor, and it is difficult to prepare ultra-thin silicon oxide layers with good uniformity, resulting in no significant improvement in the efficiency of HJT cells using ultra-thin silicon oxide layers.

[0038] In view of this, the present disclosure provides a method for preparing a solar cell, such as Figure 2 As shown, the method includes: providing a substrate, the substrate having a first surface and a second surface opposite to the first surface; forming a first hydrogenated intrinsic amorphous silicon layer on the first surface of the substrate; placing the substrate in a mixed solution of H2O2 and HF, wherein the concentration of H2O2 is greater than the concentration of HF, oxidizing and corroding the first hydrogenated intrinsic amorphous silicon layer to form a first amorphous silicon oxide layer located on the first surface of the substrate, the thickness of the first amorphous silicon oxide layer is 0.4nm to 1.5nm; forming a first doped layer on a side of the first amorphous silicon oxide layer away from the substrate; and sequentially forming a first conductive layer and a first electrode on a side of the first doped layer away from the substrate.

[0039] Next, the method for preparing the solar cell provided by the embodiment of the present disclosure is introduced.

[0040] Embodiment 1

[0041] FIG. 3A to FIG. 3B is a cross-sectional view of a solar cell during the preparation process provided by at least one embodiment of the present disclosure; Figure 3C is a cross-sectional view of a solar cell provided by at least one embodiment of the present disclosure.

[0042] The method for preparing a solar cell provided by the embodiment of the present disclosure includes:

[0043] S1, providing a substrate 1. Figure 3A As shown, the substrate 1 has a first surface 11 and a second surface 12 opposite to the first surface 11 , wherein the first surface 11 is a backlight surface and the second surface 12 is a frontlight surface.

[0044] Substrate 1 is a semiconductor substrate such as doped silicon or germanium. For example, substrate 1 is an N-type doped silicon substrate, and the corresponding dopant may include any one or more of phosphorus (P), arsenic (As), bismuth (Bi) and antimony (Sb) in group V. For another example, substrate 1 is a P-type doped silicon substrate, and the corresponding dopant may include any one or more of boron (B), aluminum (Al), gallium (Ga) and indium (In) in group III.

[0045] For example, the first surface 11 and the second surface 12 of the substrate 1 are textured. After the second surface 12 is textured, the surface area and surface complexity of the second surface 12 can be increased, thereby reducing the reflection of incident light, thereby increasing the circuit current of the battery, and further increasing the photoelectric conversion efficiency of the battery. After the first surface 11 and the second surface 12 of the substrate 1 are textured, the film layers formed on the first surface 11 have the same texture structure as the first surface 11, and the film layers formed on the second surface 12 have the same texture structure as the second surface 12.

[0046] For example, the substrate 1 is an N-type substrate, and the substrate 1 is immersed in a KOH or NaOH solution with a temperature of 60° C. to 80° C. and a mass fraction of 1% to 3% for texturing, and the texturing time is controlled to be 15 minutes to 25 minutes.

[0047] After texturing, RCA cleaning and deoxidation layer are performed.

[0048] S2, forming a first amorphous silicon oxide layer 2 on the entire first surface 11 of the substrate 1. Specifically, the step includes:

[0049] S21, such as Figure 3A As shown, a first hydrogenated intrinsic amorphous silicon layer 2 a is formed entirely on the first surface 11 of the substrate 1 .

[0050] For example, RF-PECVD (radio frequency plasma enhanced chemical vapor deposition) is used to introduce raw material gas (such as silane) and hydrogen, and after chemical reaction, a first hydrogenated intrinsic amorphous silicon layer 2a is grown on the first surface 11 of the substrate 1. For example, the thickness of the formed first hydrogenated intrinsic amorphous silicon layer 2a is 5nm to 20nm.

[0051] S22, placing the substrate 1 having the first hydrogenated intrinsic amorphous silicon layer 2a into a mixed solution of H2O2 and HF to obtain a first amorphous silicon oxide layer 2 (such as Figure 3B shown).

[0052] Among them, the concentration of H2O2 is greater than the concentration of HF. For example, the molar ratio of H2O2 and HF is (4-6):1, preferably 5:1. H2O2 is mainly used to react with silicon in the first hydrogenated intrinsic amorphous silicon layer 2a to form silicon oxide, and HF is mainly used to corrode the generated silicon oxide. The two act simultaneously to oxidize and corrode the first hydrogenated intrinsic amorphous silicon layer 2a, thereby gradually thinning the thickness of the first hydrogenated intrinsic amorphous silicon layer 2a. Since the concentration of H2O2 is higher, the generation rate of silicon oxide is greater than the corrosion rate, and finally the first amorphous silicon oxide layer 2 located on the first surface 11 of the substrate 1 can be formed. For example, the reaction time is 25s to 35s, preferably 30s.

[0053] In the present disclosure, the first amorphous silicon oxide layer 2 is formed by gradually thinning a thicker first hydrogenated intrinsic amorphous silicon layer 2a by oxidation and corrosion. The obtained ultra-thin first amorphous silicon oxide layer 2 has a relatively uniform thickness and has the same shape as the velvet morphology of the first surface 11, which solves the difficulty of preparing an ultra-thin silicon oxide layer with uniform thickness in the known technology.

[0054] S3, forming a third hydrogenated intrinsic amorphous silicon layer 3 (such as Figure 3C shown).

[0055] In some cases, the ultra-thin first amorphous silicon oxide layer 2 is difficult to provide an effective passivation effect. After the third hydrogenated intrinsic amorphous silicon layer 3 is provided, the passivation effect of the solar cell can be improved. In addition, since the passivation effect of the first amorphous silicon oxide layer 2 is better than that of the third hydrogenated intrinsic amorphous silicon layer 3, under the premise of achieving the same passivation effect, after the first amorphous silicon oxide layer 2 is provided, the thickness of the third hydrogenated intrinsic amorphous silicon layer 3 required to be provided is thinner, and the contact resistance of the solar cell will also be reduced due to the thinning of the thickness of the third hydrogenated intrinsic amorphous silicon layer 3, thereby improving the fill factor and short-circuit current density of the solar cell. For example, the thickness of the third hydrogenated intrinsic amorphous silicon layer 3 is between 3nm and 5nm.

[0056] S4, forming a first doping layer 4 (such as Figure 3C shown).

[0057] For example, PECVD is used to introduce raw material gas (such as SiCl4, SiHCl3 or SiH4), doping gas (such as trimethylborane or diborane) and hydrogen, and after chemical reaction, a P-type doped first doping layer 4 is grown on the third hydrogenated intrinsic amorphous silicon layer 3. For example, VHF-PECVD (very high frequency plasma enhanced chemical vapor deposition) is used to form the material of the first doping layer 4, which is hydrogenated microcrystalline silicon. Of course, the material of the first doping layer 4 can also be hydrogenated amorphous silicon or hydrogenated oxygen-doped amorphous silicon. For example, the thickness of the first doping layer 4 is between 10nm and 20nm.

[0058] S5 . Form a second amorphous silicon oxide layer 5 on the second surface 12 of the substrate 1 . Specifically include:

[0059] S51, forming a second hydrogenated intrinsic amorphous silicon layer 5a (eg, Figure 3A For example, the thickness of the formed second hydrogenated intrinsic amorphous silicon layer 5a is 5 nm to 20 nm.

[0060] S52, placing the substrate 1 having the second hydrogenated intrinsic amorphous silicon layer 5a into a mixed solution of H2O2 and HF to obtain a second amorphous silicon oxide layer 5 (such as Figure 3B shown).

[0061] The concentration of H2O2 is greater than that of HF. For example, the molar ratio of H2O2 to HF is (4-6):1, preferably 5:1. For example, the reaction time is 25s to 35s, preferably 30s.

[0062] For example, step S51 and step S21 can be performed in the same process step of the same device, and step S52 and step S22 can be performed in the same process step of the same device.

[0063] S6, forming a fourth hydrogenated intrinsic amorphous silicon layer 6 (eg, Figure 3C As shown), the passivation effect of the solar cell on the front side is improved.

[0064] S7, forming a second doping layer 7 (such as Figure 3C shown).

[0065] For example, PECVD is used to introduce raw material gas (such as SiCl4, SiHCl3 or SiH4), doping gas (such as PH3 and N2O) and hydrogen, and after chemical reaction, an N-type doped second doping layer 7 is grown on the fourth hydrogenated intrinsic amorphous silicon layer 6. Among them, the material of the second doping layer 7 is hydrogenated oxygen-doped microcrystalline silicon, which helps to reduce the parasitic absorption of the second doping layer 7, thereby improving the efficiency of the solar cell. In addition, the material of the second doping layer 7 can also be hydrogenated amorphous silicon, hydrogenated microcrystalline silicon, hydrogenated microcrystalline silicon carbide or hydrogenated carbon-doped microcrystalline silicon oxide, among which hydrogenated microcrystalline silicon carbide or hydrogenated carbon-doped microcrystalline silicon oxide is often used as the material of the N-type doping layer because the type of its own material is N-type. For example, the thickness of the second doping layer 7 is between 10nm and 20nm.

[0066] S8, forming a first conductive layer 81 on the side of the first doping layer 4 away from the substrate 1, and forming a second conductive layer 82 on the side of the second doping layer 7 away from the substrate 1 (eg Figure 3C shown).

[0067] For example, the first conductive layer 81 or the second conductive layer 82 can be formed by PVD (physical vapor deposition), RPD (rapid plasma deposition) or evaporation, and the thickness is between 60nm and 80nm. For example, the first conductive layer 81 or the second conductive layer 82 can be a single-layer structure or a multi-layer structure. The material of the first conductive layer 81 and the second conductive layer 82 is TCO (Transparent Conductive Oxides, transparent conductive film), and the material of each layer in the first conductive layer 81 or the second conductive layer 82 can be specifically one of ITO (Indium tin oxide, indium tin oxide), ICO (indium oxide doped with cadmium), IWO (indium oxide doped with tungsten), SnO2, etc.

[0068] S9, forming a first electrode 91 and a second electrode 92. The first electrode 91 is located on the back side of the solar cell and is electrically connected to the first conductive layer 81; the second electrode 92 is located on the front side of the solar cell and is electrically connected to the second conductive layer 82.

[0069] like Figure 3C As shown, the present disclosure further discloses a solar cell, including a substrate 1 , wherein the substrate 1 has a first surface 11 and a second surface 12 opposite to the first surface 11 .

[0070] The first surface 11 of the substrate 1 is provided with a first amorphous silicon oxide layer 2, a first doped layer 4, a first conductive layer 81 and a first electrode 91 in sequence. The first electrode 91 is electrically connected to the first conductive layer 81. The thickness of the first amorphous silicon oxide layer 2 is between 0.4 nm and 1.5 nm, preferably between 0.5 nm and 1 nm. The thickness of the first doped layer 4 is between 10 nm and 20 nm, and the thickness of the first conductive layer 81 is between 60 nm and 80 nm.

[0071] The second surface 12 of the substrate 1 is provided with a second amorphous silicon oxide layer 5, a second doped layer 7, a second conductive layer 82 and a second electrode 92 in sequence. The second doped layer 7 has a doping type opposite to that of the first doped layer 4, and the second electrode 92 is electrically connected to the second conductive layer 82. The thickness of the second amorphous silicon oxide layer 5 is between 0.4 nm and 1.5 nm, preferably between 0.5 nm and 1 nm. The thickness of the second doped layer 7 is between 10 nm and 20 nm, and the thickness of the second conductive layer 82 is between 60 nm and 80 nm.

[0072] In some examples, a third hydrogenated intrinsic amorphous silicon layer 3 is disposed between the first amorphous silicon oxide layer 2 and the first doped layer 4 to improve the passivation effect of the back side of the solar cell. A fourth hydrogenated intrinsic amorphous silicon layer 6 is disposed between the second amorphous silicon oxide layer 5 and the second doped layer 7 to improve the passivation effect of the front side of the solar cell. The thickness of the third hydrogenated intrinsic amorphous silicon layer 3 is between 3 nm and 5 nm, and the thickness of the fourth hydrogenated intrinsic amorphous silicon layer 6 is between 3 nm and 5 nm.

[0073] For example, the thickness of the first amorphous silicon oxide layer 2 and the second amorphous silicon oxide layer 5 are both 1nm, the thickness of the third hydrogenated intrinsic amorphous silicon layer 3 and the fourth hydrogenated intrinsic amorphous silicon layer 6 are both 5nm, the first doped layer 4 is P-type doped and has a thickness of 10nm, and the second doped layer 7 is N-type doped and has a thickness of 10nm. Its cell efficiency is 25.16%, the open circuit voltage is 748mV, the fill factor is 85.4%, and the short circuit current density is 39.4mA / cm 2 . Table 1

[0074] By comparing with the comparative examples in the known technology, it can be seen that under the premise of achieving the same open circuit voltage, the thickness of the passivation layer used in the solar cell of the embodiment of the present disclosure is thinner. Since the thickness of the hydrogenated intrinsic amorphous silicon layer (specifically the third hydrogenated intrinsic amorphous silicon layer 3 or the fourth hydrogenated intrinsic amorphous silicon layer 6) in the solar cell is thinner than the hydrogenated intrinsic amorphous silicon layer (specifically the first intrinsic amorphous silicon layer 3' or the second intrinsic amorphous silicon layer 6') in the known technology, the series resistance of the solar cell in the embodiment of the present disclosure is lower, and the fill factor, short-circuit current density and cell efficiency are all improved.

[0075] Embodiment 2

[0076] Figure 4A is a cross-sectional view of a solar cell during the preparation process provided by at least one embodiment of the present disclosure; Figure 4B is another cross-sectional view of a solar cell provided in at least one embodiment of the present disclosure.

[0077] The present disclosure provides a method for preparing a solar cell, wherein steps S1 to S4 are the same as steps S1 to S4 in the method for preparing a solar cell provided in embodiment 1. Figure 4A and Figure 4B As shown, the substrate 1 has a first doping region 13, a second doping region 14 and an isolation region 15 located between the first doping region 13 and the second doping region 14, the first doping layer 4 is located in the first doping region 13, and the first amorphous silicon oxide layer 2 and the third hydrogenated intrinsic amorphous silicon layer 3 cover the first doping region 13, the second doping region 14 and the isolation region 15.

[0078] The method for preparing a solar cell provided in the embodiment of the present disclosure further includes:

[0079] S5. Sequentially form an intrinsic passivation layer 10 and an anti-reflection layer 20 on the second surface 12 of the substrate 1. The intrinsic passivation layer 10 is amorphous silicon, and the anti-reflection layer 20 is silicon nitride or silicon oxide. For example, the intrinsic passivation layer 10 and the anti-reflection layer 20 are formed by PECVD (plasma enhanced chemical vapor deposition).

[0080] S6. Form a second doping layer 7 located in the second doping region 14 on a side of the third hydrogenated intrinsic amorphous silicon layer 3 away from the substrate 1. The second doping layer 7 and the first doping layer 4 are arranged in parallel in the first direction X.

[0081] For example, PECVD is used to introduce raw material gas (such as SiCl4, SiHCl3 or SiH4), doping gas (such as PH3 and N2O) and hydrogen, and after chemical reaction, a material layer of the N-type doped second doping layer 7 is grown on the material layer of the fourth hydrogenated intrinsic amorphous silicon layer 6, and then a patterning process is performed to form the second doping layer 7 located in the second doping region 14. Among them, the material of the second doping layer 7 is hydrogenated oxygen-doped microcrystalline silicon, which helps to reduce the parasitic absorption of the second doping layer 7, thereby improving the efficiency of the solar cell. In addition, the material of the second doping layer 7 can also be hydrogenated amorphous silicon or hydrogenated microcrystalline silicon. For example, the thickness of the second doping layer 7 is between 10nm and 20nm.

[0082] S7 . Form a first conductive layer 81 and a second conductive layer 82 that are insulated from each other. The first conductive layer 81 is electrically connected to the first doping layer 4 , and the second conductive layer 82 is electrically connected to the second doping layer 7 .

[0083] S8, forming a first electrode 91 and a second electrode 92. The first electrode 91 is located on the back side of the solar cell and is electrically connected to the first conductive layer 81; the second electrode 92 is located on the back side of the solar cell and is electrically connected to the second conductive layer 82.

[0084] like Figure 4B As shown, the present disclosure also discloses a solar cell, including a substrate 1, the substrate 1 having a first surface 11 and a second surface 12 opposite to the first surface 11, the substrate 1 having a first doping region 13, a second doping region 14 and an isolation region 15 located between the first doping region 13 and the second doping region 14.

[0085] An intrinsic passivation layer 10 and an anti-reflection layer 20 are sequentially disposed on the second surface 12 of the substrate 1 .

[0086] A first amorphous silicon oxide layer 2 is provided on the first surface 11 of the substrate 1. A first doping layer 4 and a second doping layer 7 are provided on the side of the first amorphous silicon oxide layer 2 away from the substrate 1 and arranged in parallel along the first direction X. The doping types of the first doping layer 4 and the second doping layer 7 are opposite, the first doping layer 4 is located in the first doping region 13, the second doping layer 7 is located in the second doping region 14, and the isolation region 15 can isolate the first doping layer 4 and the second doping layer 7 for electrical insulation. A first conductive layer 81 is provided on the side of the first doping layer 4 away from the substrate 1, and the first conductive layer 81 is electrically connected to the first electrode 91. A second conductive layer 82 is provided on the side of the second doping layer 7 away from the substrate 1, and the second conductive layer 82 is electrically connected to the second electrode 92.

[0087] In some examples, a third hydrogenated intrinsic amorphous silicon layer 3 is further provided on the side of the first amorphous silicon oxide layer 2 away from the substrate 1. The third hydrogenated intrinsic amorphous silicon layer 3 is provided on the entire surface and is located between the first doped layer 4 and the first amorphous silicon oxide layer 2 and between the second doped layer 7 and the first amorphous silicon oxide layer 2 to enhance the passivation effect of the solar cell.

[0088] There are a few points to note:

[0089] (1) The drawings of the embodiments of the present disclosure only relate to the structures related to the embodiments of the present disclosure, and other structures may refer to the general design.

[0090] (2) For the sake of clarity, in the drawings used to describe the embodiments of the present disclosure, the thickness of layers or regions is exaggerated or reduced, that is, these drawings are not drawn according to the actual scale. It is understood that when an element such as a layer, film, region or substrate is referred to as being "on" or "under" another element, the element may be "directly" "on" or "under" the other element or there may be intermediate elements.

[0091] (3) In the absence of conflict, the embodiments of the present disclosure and the features therein may be combined with each other to obtain new embodiments.

[0092] The above is only a specific implementation of the present disclosure, but the protection scope of the present disclosure is not limited thereto. Any person skilled in the art who is familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the present disclosure, which should be included in the protection scope of the present disclosure. Therefore, the protection scope of the present disclosure should be based on the protection scope of the claims.

Claims

1. A method for preparing a solar cell, characterized in that: include: providing a substrate having a first surface and a second surface opposite to the first surface; forming a first hydrogenated intrinsic amorphous silicon layer on the entire first surface of the substrate; The substrate is placed in a mixed solution of H2O2 and HF, wherein the concentration of H2O2 is greater than the concentration of HF, and the first hydrogenated intrinsic amorphous silicon layer is oxidized and corroded to form a first amorphous silicon oxide layer located on the first surface of the substrate, wherein the thickness of the first amorphous silicon oxide layer is 0.4nm to 1.5nm.

2. The method for preparing a solar cell according to claim 1, characterized in that: The preparation method further comprises: forming a second hydrogenated intrinsic amorphous silicon layer on the second surface of the substrate; In the process of placing the substrate in a mixed solution of H2O2 and HF, the second hydrogenated intrinsic amorphous silicon layer is oxidized and corroded to form a second amorphous silicon oxide layer located on the second surface of the substrate, and the thickness of the second amorphous silicon oxide layer is 0.4nm to 1.5nm.

3. The method for preparing a solar cell according to claim 1 or 2, characterized in that: The molar ratio of H2O2 and HF is (4-6):

1.

4. The method for preparing a solar cell according to claim 2, characterized in that: The preparation method further comprises: forming a first doping layer, a first conductive layer and a first electrode on a side of the first amorphous silicon oxide layer away from the substrate; A second doping layer, a second conductive layer and a second electrode are sequentially formed on a side of the second amorphous silicon oxide layer away from the substrate, wherein the doping type of the second doping layer is opposite to that of the first doping layer.

5. The method for preparing a solar cell according to claim 1, characterized in that: The preparation method further comprises: forming a first doped layer on a side of the first amorphous silicon oxide layer away from the substrate, and sequentially forming a first conductive layer and a first electrode on a side of the first doped layer away from the substrate; forming a second doping layer on a side of the first amorphous silicon oxide layer away from the substrate, wherein the doping type of the second doping layer is opposite to the doping type of the first doping layer, and the first doping layer and the second doping layer are arranged side by side in a first direction and insulated from each other; A second conductive layer and a second electrode are sequentially formed on a side of the second doped layer away from the substrate.

6. The method for preparing a solar cell according to claim 4 or 5, characterized in that: The thickness of the first hydrogenated intrinsic amorphous silicon layer and the second hydrogenated intrinsic amorphous silicon layer is 5 nm to 20 nm, and the reaction time of placing the substrate in the mixed solution of H2O2 and HF is 25 s to 35 s.

7. The method for preparing a solar cell according to claim 1, characterized in that: The preparation method further comprises: Before forming the first doping layer, a third hydrogenated intrinsic amorphous silicon layer is formed on a side of the first amorphous silicon oxide layer away from the substrate.

8. The method for preparing a solar cell according to claim 4, characterized in that: The preparation method further comprises: Before forming the second doping layer, a fourth hydrogenated intrinsic amorphous silicon layer is formed on a side of the second amorphous silicon oxide layer away from the substrate.

9. The method for preparing a solar cell according to claim 4 or 5, characterized in that: The material of the first doping layer is hydrogenated amorphous silicon, hydrogenated microcrystalline silicon or hydrogenated oxygen-doped microcrystalline silicon; and / or, The material of the second doping layer is hydrogenated amorphous silicon, hydrogenated microcrystalline silicon, hydrogenated oxygen-doped microcrystalline silicon, hydrogenated microcrystalline silicon carbide or hydrogenated carbon-doped microcrystalline silicon oxide.

10. A solar cell, characterized in that: Prepared by the preparation method according to any one of claims 1 to 9, comprising: a substrate having a first surface and a second surface opposite to the first surface; The first amorphous silicon oxide layer is disposed on the entire surface and located on the first surface of the substrate, and has a thickness of 0.4 nm to 1.5 nm.

11. The solar cell according to claim 10, characterized in that Also includes: A first doped layer, located on a side of the first amorphous silicon oxide layer away from the substrate; A first conductive layer, located on a side of the first doped layer away from the substrate; a first electrode, electrically connected to the first conductive layer; A second amorphous silicon oxide layer, located on the second surface of the substrate, with a thickness of 0.4 nm to 1.5 nm; A second doped layer is located on a side of the second amorphous silicon oxide layer away from the substrate; a second conductive layer, located on a side of the second doped layer away from the substrate; The second electrode is electrically connected to the second conductive layer.

12. The solar cell according to claim 10, characterized in that: Also includes: A first doped layer, located on a side of the first amorphous silicon oxide layer away from the substrate; A first conductive layer, located on a side of the first doped layer away from the substrate; a first electrode, electrically connected to the first conductive layer; a second doped layer, located on a side of the first amorphous silicon oxide layer away from the substrate, and arranged in parallel with the first doped layer in a first direction and insulated from each other; a second conductive layer, located on a side of the second doped layer away from the substrate; The second electrode is electrically connected to the second conductive layer.

13. The solar cell according to claim 11 or 12, characterized in that: A third hydrogenated intrinsic amorphous silicon layer is disposed between the first amorphous silicon oxide layer and the first doping layer.

Images