Photovoltaic cell and its preparation method

Abstract

Embodiments of the present disclosure relate to the field of photovoltaics, and provide a photovoltaic cell and a preparation method thereof. The preparation method includes: providing a battery chip body, the battery chip body including a substrate having opposite first and second surfaces, a first aluminum oxide layer located on the first surface, and a second aluminum oxide layer located on the second surface; irradiating at least one of the first surface and the second surface with first light to perform a first photothermal annealing treatment on the battery chip body; then performing a laser enhanced contact treatment on the battery chip body; irradiating at least one of the first surface and the second surface with second light to perform a second photothermal annealing treatment on the battery chip body; wherein the wavelength of the first light is greater than the wavelength of the second light. Embodiments of the present disclosure are at least beneficial to improving the photoelectric conversion efficiency of the photovoltaic cell.

Description

Technical Field

[0001] The present disclosure relates to the field of photovoltaics, and particularly to a photovoltaic cell and a method for manufacturing the same. Background Art

[0002] With the gradual depletion of fossil energy, photovoltaic cells, as a new energy alternative, are being used more and more widely. A photovoltaic cell is a device that converts the light energy of the sun into electrical energy. The photovoltaic cell utilizes the photovoltaic effect to generate carriers, and then uses electrodes to extract the carriers, thereby facilitating the effective utilization of electrical energy.

[0003] Currently, the main types of photovoltaic cells include IBC cells (Interdigitated BackContact), TOPCON (Tunnel Oxide Passivated Contact) cells, PERC cells (Passivated emitter and real cell), and heterojunction cells, etc.

[0004] However, the photoelectric conversion efficiencies of photovoltaic cells formed by different manufacturing methods are different, and it is necessary to develop a manufacturing method that is more conducive to improving the photoelectric conversion efficiency of photovoltaic cells. Summary of the Invention

[0005] Embodiments of the present disclosure provide a photovoltaic cell and a method for manufacturing the same, which are at least conducive to improving the photoelectric conversion efficiency of the photovoltaic cell.

[0006] According to some embodiments of the present disclosure, on the one hand, a method for manufacturing a photovoltaic cell is provided, including: providing a battery chip body, the battery chip body including a substrate having opposite first and second surfaces, a first aluminum oxide layer located on the first surface, and a second aluminum oxide layer located on the second surface; irradiating at least one of the first surface and the second surface with a first light ray to perform a first photothermal annealing treatment on the battery chip body; then performing a laser enhanced contact treatment on the battery chip body; irradiating at least one of the first surface and the second surface with a second light ray to perform a second photothermal annealing treatment on the battery chip body; wherein, the wavelength of the first light ray is greater than the wavelength of the second light ray.

[0007] In some embodiments, the step of performing the first photothermal annealing treatment at least includes irradiating the first surface with the first light ray; and / or, at least a part of the surface of the second surface is a polished surface, and the step of performing the second photothermal annealing treatment at least includes irradiating the second surface with the second light ray.

[0008] In some embodiments, the steps of performing the first photothermal annealing treatment include: providing a first light source and a second light source, where the first light source is used to irradiate the first surface, the second light source is used to irradiate the second surface, and the first light ray includes a first sub-ray provided by the first light source and a second sub-ray provided by the second light source; and / or, the steps of performing the second photothermal annealing treatment include: providing a third light source and a fourth light source, where the third light source is used to irradiate the first surface, the fourth light source is used to irradiate the second surface, and the second light ray includes a third sub-ray provided by the third light source and a fourth sub-ray provided by the fourth light source.

[0009] In some embodiments, at least one of the light wavelength, light intensity density, and irradiation time provided by both the first light source and the second light source is different; and / or, at least one of the light wavelength, light intensity density, and irradiation time provided by both the third light source and the fourth light source is different.

[0010] In some embodiments, the light intensity density provided by the first light source is less than the light intensity density provided by the second light source; and / or, the light intensity density provided by the third light source is less than the light intensity density provided by the fourth light source.

[0011] In some embodiments, the light intensity density provided by the first light source is 4 kW / m 2 ~8 kW / m 2 and the light intensity density provided by the second light source is 10 kW / m 2 ~18 kW / m 2 .

[0012] In some embodiments, the steps of providing the battery cell body further include: forming a first passivation layer on a side of the first aluminum oxide layer away from the first surface; and / or, forming a second passivation layer on a side of the second aluminum oxide layer away from the second surface; where the first passivation layer and / or the second passivation layer includes at least one of a silicon nitride layer, a silicon oxynitride layer, or a silicon oxide layer.

[0013] In some embodiments, the wavelength of the first light ray is 800 nm to 1000 nm, and the wavelength of the second light ray is 365 nm to 400 nm.

[0014] In some embodiments, the heating temperature of the first photothermal annealing treatment is greater than the heating temperature of the second photothermal annealing treatment.

[0015] According to some embodiments of the present disclosure, on the other hand, the present disclosure embodiments further provide a photovoltaic cell, including: a photovoltaic cell formed according to the preparation method described in any one of the above.

[0016] The technical solutions provided by the embodiments of the present disclosure have at least the following advantages:

[0017] On the one hand, compared with the second light ray used in the second photothermal annealing treatment, the wavelength of the first light ray used in the first photothermal annealing treatment is larger, so the photon energy of the first light ray is greater, which is beneficial to deeply activate the first aluminum oxide layer and / or the second aluminum oxide layer. For example, it can increase the content of hydrogen ions in the first aluminum oxide layer and / or the second aluminum oxide layer to improve the passivation effect of the first aluminum oxide layer and / or the second aluminum oxide layer on the surface of the substrate. On the other hand, compared with the first light ray used in the first photothermal annealing treatment, the wavelength of the second light ray used in the second photothermal annealing treatment is smaller, and the second light ray is not sufficient to break the silicon-hydrogen bond on the surface of the substrate. The second light ray is incident on the shallow surface of the photovoltaic cell to perform secondary activation on the first aluminum oxide layer and / or the second aluminum oxide layer, which is beneficial to improving the contact performance between the electrode and the substrate. For example, it can reduce the probability of metal recombination between the electrode and the substrate. On the other hand, performing the first photoannealing treatment and the second photoannealing treatment at intervals before and after the laser enhanced contact treatment is beneficial to improving the lifetime of minority carriers. In this way, the combined effect of multiple aspects is beneficial to improving the photoelectric conversion efficiency of the finally prepared photovoltaic cell. Description of the Drawings

[0018] One or more embodiments are exemplarily illustrated by the pictures in the corresponding drawings. These exemplary illustrations do not limit the embodiments unless otherwise stated. The figures in the drawings do not constitute a proportional limitation. To more clearly illustrate the technical solutions in the embodiments of the present disclosure or the prior art, the following will briefly introduce the drawings required for use in the embodiments. Obviously, the following described drawings are only some embodiments of the present disclosure. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0019] Figure 1 It is a schematic partial cross-sectional structure diagram of a battery chip body in the preparation method of a photovoltaic cell provided by an embodiment of the present disclosure;

[0020] Figure 2 It is another schematic partial cross-sectional structure diagram of a battery chip body in the preparation method of a photovoltaic cell provided by an embodiment of the present disclosure. Detailed Embodiments

[0021] As can be seen from the background art, the photoelectric conversion efficiency of photovoltaic cells needs to be improved.

[0022] The present disclosure provides a photovoltaic cell and a method for manufacturing the same. In the manufacturing method, on the one hand, compared with the second light used in the second photothermal annealing treatment, the wavelength of the first light used in the first photothermal annealing treatment is larger, so the photon energy of the first light is greater, which is beneficial to deeply activate the first aluminum oxide layer and / or the second aluminum oxide layer. For example, it can increase the content of hydrogen ions in the first aluminum oxide layer and / or the second aluminum oxide layer to improve the passivation effect of the first aluminum oxide layer and / or the second aluminum oxide layer on the surface of the substrate. On the other hand, compared with the first light used in the first photothermal annealing treatment, the wavelength of the second light used in the second photothermal annealing treatment is smaller, and the second light is not sufficient to break the silicon-hydrogen bonds on the surface of the substrate. The second light is incident on the shallow surface of the photovoltaic cell to perform secondary activation on the first aluminum oxide layer and / or the second aluminum oxide layer, which is beneficial to improving the contact performance between the electrode and the substrate. For example, it can reduce the probability of metal recombination between the electrode and the substrate. On the other hand, performing the first photoannealing treatment and the second photoannealing treatment at intervals before and after the laser enhanced contact treatment is beneficial to improving the lifetime of minority carriers. In this way, the combined action of multiple aspects is beneficial to improving the photoelectric conversion efficiency of the finally manufactured photovoltaic cell.

[0023] In the description of the embodiments of the present disclosure, technical terms such as "first" and "second" are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity, specific order or primary-secondary relationship of the indicated technical features. In the description of the embodiments of the present disclosure, the meaning of "a plurality" is more than two, unless otherwise clearly and specifically defined.

[0024] Referring to "embodiments" herein means that the specific features, structures or characteristics described in connection with the embodiments can be included in at least one embodiment of the present disclosure. The phrase appears in various places in the specification and does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments. Those skilled in the art will explicitly and implicitly understand that the embodiments described herein can be combined with other embodiments.

[0025] In the description of the embodiments of the present disclosure, the term "and / or" is only a description of the association relationship of the associated objects, indicating that there can be three relationships. For example, A and / or B can mean: there is A, there is both A and B, and there is B. In addition, the character " / " in this article generally represents an "or" relationship between the associated objects before and after.

[0026] In the description of the embodiments of the present disclosure, the term "a plurality" refers to more than two (including two). Similarly, "a plurality of groups" refers to more than two groups (including two groups), and "a plurality of pieces" refers to more than two pieces (including two pieces).

[0027] In the description of the embodiments of the present disclosure, the orientation or positional relationship indicated by technical terms such as "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the embodiments of the present disclosure and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation on the embodiments of the present disclosure.

[0028] In the description of the embodiments of the present disclosure, unless otherwise clearly specified and limited, technical terms such as "installation", "connection", "coupling", "fixation", etc. should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can also be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of the present disclosure can be understood according to specific circumstances.

[0029] In the corresponding drawings of the embodiments of the present disclosure, for better understanding and convenience of description, the thickness and area of the layer are enlarged. When describing a component (such as a layer, film, region, or substrate) on or on the surface of another component, the component can be "directly" on the surface of the other component, or there can be a third component between the two components. On the contrary, when describing a component on the surface of another component or when another component is formed or provided on the surface of a component, it means that there is no third component between the two components. In addition, when describing a component "substantially" formed on another component, it means that the component is not formed on the entire surface (or front surface) of the other component, nor on a partial edge of the entire surface.

[0030] In the description of the embodiments of the present disclosure, when a certain component "includes" another component, unless otherwise stated, other components are not excluded, and other components may further be included. In addition, when a component such as a layer, film, region, or plate is referred to as "on / at" another component, it can be "directly on" the other component (that is, on the surface of the other component and there is no other component between them), or there can be another component between them. In addition, when a component such as a layer, film, region, or plate is "directly located on" another component, or when a component such as a layer, film, region, or plate is located on the surface of another component, it means that there is no other component between them.

[0031] The terms used in the description of the various embodiments herein are for the purpose of describing particular embodiments only and are not intended to be limiting. As used in the description of the various embodiments and the appended claims, "the component" is also intended to include the plural form unless the context clearly indicates otherwise. Among them, the component includes components such as layers, films, regions, or plates.

[0032] The embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings. However, those of ordinary skill in the art can understand that in the embodiments of the present disclosure, many technical details are provided to help readers better understand the embodiments of the present disclosure. However, even without these technical details and various changes and modifications based on the following embodiments, the technical solutions claimed in the embodiments of the present disclosure can still be implemented.

[0033] An embodiment of the present disclosure provides a method for preparing a photovoltaic cell. The method for preparing the photovoltaic cell provided by an embodiment of the present disclosure will be described in detail below with reference to the accompanying drawings.

[0034] Reference Figure 1 or Figure 2 , the method for preparing a photovoltaic cell includes the following steps: providing a battery chip body 100, the battery chip body 100 including a substrate 101 having opposite first and second surfaces 111 and 121, a first aluminum oxide layer 102 located on the first surface 111, and a second aluminum oxide layer 103 located on the second surface 121; irradiating at least one of the first surface 111 and the second surface 121 with a first light ray to perform a first photothermal annealing treatment on the battery chip body 100; then performing a laser enhanced contact treatment on the battery chip body 100; irradiating at least one of the first surface 111 and the second surface 121 with a second light ray to perform a second photothermal annealing treatment on the battery chip body 100; wherein, the wavelength of the first light ray is greater than the wavelength of the second light ray.

[0035] Among them, Figure 1 is a schematic diagram of a partial cross-sectional structure of the battery chip body in the method for preparing a photovoltaic cell provided by an embodiment of the present disclosure; Figure 2 is another schematic diagram of a partial cross-sectional structure of the battery chip body in the method for preparing a photovoltaic cell provided by an embodiment of the present disclosure.

[0036] It should be noted that, on the one hand, compared with the second light used in the second photothermal annealing treatment, the wavelength of the first light used in the first photothermal annealing treatment is larger, so the photon energy of the first light is greater, which is beneficial to deeply activate the first alumina layer 102 and / or the second alumina layer 103. For example, it can increase the content of hydrogen ions in the first alumina layer 102 and / or the second alumina layer 103 to improve the passivation effect of the first alumina layer 102 and / or the second alumina layer 103 on the surface of the substrate 101. For example, it can increase the probability of the recombination of hydrogen ions and the surface defects of the substrate 101 to achieve the passivation of the surface of the substrate 101. On the other hand, compared with the first light used in the first photothermal annealing treatment, the wavelength of the second light used in the second photothermal annealing treatment is smaller, and the second light is not sufficient to break the silicon-hydrogen bonds on the surface of the substrate 101. The second light is incident on the shallow surface of the photovoltaic cell to perform secondary activation on the first alumina layer 102 and / or the second alumina layer 103, which is beneficial to improving the contact performance between the electrode and the substrate 101. For example, it can reduce the probability of metal recombination between the electrode and the substrate 101. On the other hand, performing the first photoannealing treatment and the second photoannealing treatment at intervals before and after the laser enhanced contact treatment is beneficial to improving the lifetime of minority carriers. In this way, the combined action of multiple aspects is beneficial to improving the photoelectric conversion efficiency of the finally prepared photovoltaic cell.

[0037] In some examples, the photoelectric conversion efficiency of the photovoltaic cell formed by using the preparation method of the photovoltaic cell provided in an embodiment of the present disclosure can be increased by about 0.03% - 0.05%.

[0038] The following will detail each step in the preparation method of the photovoltaic cell provided in an embodiment of the present disclosure:

[0039] In some embodiments, referring to Figure 2 , the step of providing the battery cell body 100 may further include: forming a first passivation layer 104 on the side of the first alumina layer 102 away from the first surface 111; and / or forming a second passivation layer 105 on the side of the second alumina layer 103 away from the second surface 121; wherein, the first passivation layer 104 and / or the second passivation layer 105 may include at least one of a silicon nitride layer, a silicon oxynitride layer, or a silicon oxide layer.

[0040] It should be emphasized that the first photothermal annealing treatment and the second photothermal annealing treatment can respectively activate the first alumina layer 102 and / or the second alumina layer 103 to enhance the passivation effect of the first alumina layer 102 and / or the second alumina layer 103 on the substrate 101. Similarly, the first photothermal annealing treatment and the second photothermal annealing treatment can respectively activate the first passivation layer 104 and / or the second passivation layer 105, for example, by increasing the content of ions in the first passivation layer 104 and / or the second passivation layer 105 that can achieve a passivation effect, thereby further increasing the probability that surface defects of the substrate 101 are passivated by ions, and thus enhancing the overall passivation effect of the photovoltaic cell.

[0041] It should be noted that Figure 2 in the example where the first passivation layer 104 is formed on the side of the first alumina layer 102 away from the first surface 111, and the second passivation layer 105 is formed on the side of the second alumina layer 103 away from the second surface 121. In practical applications, only the first passivation layer may be formed on the side of the first alumina layer away from the first surface, or only the second passivation layer may be formed on the side of the second alumina layer away from the second surface.

[0042] In some embodiments, the step of providing the cell body 100 may further include: disposing electrode paste on the cell body 100; performing electrode metallization on the electrode paste to form electrodes (not shown in the figure) on at least one of the first surface 111 and the second surface 121.

[0043] In some examples, the step of disposing electrode paste on the cell body 100 may include: disposing electrode paste on the cell body 100 using a screen printing process, or disposing electrode paste on the cell body 100 using an electroplating process. In some instances, the electrode paste may include at least one of silver, aluminum, copper, tin, gold, lead, or nickel.

[0044] In some examples, the step of performing electrode metallization on the electrode paste may include: performing a sintering process on the electrode paste. In some cases, the electrode paste contains materials with highly corrosive components such as glass. Thus, during the sintering process, the corrosive components will corrode the first alumina layer 102 and the first passivation layer 104, causing the finally formed electrode to embed into the first alumina layer 102 and the first passivation layer 104; and / or, during the sintering process, the corrosive components will corrode the second alumina layer 103 and the second passivation layer 105, causing the finally formed electrode to embed into the second alumina layer 103 and the second passivation layer 105.

[0045] In some embodiments, the material of the substrate 101 may be an elemental semiconductor material. Specifically, the elemental semiconductor material is composed of a single element, such as silicon or germanium. Among them, the elemental semiconductor material may be in single crystal state, polycrystalline state, amorphous state or microcrystalline state (a state with both single crystal state and amorphous state is called microcrystalline state). For example, silicon may be at least one of single crystal silicon, polycrystalline silicon, amorphous silicon or microcrystalline silicon.

[0046] In some other embodiments, the material of the substrate 101 may also be a compound semiconductor material. Common compound semiconductor materials include, but are not limited to, silicon germanide, silicon carbide, gallium arsenide, indium gallium, perovskite, cadmium telluride, copper indium selenide and other materials.

[0047] In some embodiments, the substrate 101 may be an N-type semiconductor substrate or a P-type semiconductor substrate. The N-type semiconductor substrate is doped with N-type doping elements, and the N-type doping elements may be at least one of group V elements such as phosphorus (P) element, bismuth (Bi) element, antimony (Sb) element or arsenic (As) element. The P-type semiconductor substrate is doped with P-type elements, and the P-type doping elements may be at least one of group III elements such as boron (B) element, aluminum (Al) element, gallium (Ga) element or indium (In) element.

[0048] In some embodiments, the wavelength of the first light ray used in the first photothermal annealing treatment may be 800 nm to 1000 nm. For example, the wavelength of the first light ray may be 810 nm, 820 nm, 830 nm, 840 nm, 850 nm, 860 nm, 870 nm, 880 nm, 890 nm, 900 nm, 910 nm, 920 nm, 930 nm, 940 nm, 950 nm, 960 nm, 970 nm, 980 nm or 990 nm, etc.; the wavelength of the second light ray used in the second photothermal annealing treatment may be 365 nm to 400 nm. For example, the wavelength of the second light ray may be 370 nm, 372 nm, 375 nm, 376 nm, 378 nm, 380 nm, 383 nm, 385 nm, 386 nm, 390 nm, 392 nm, 395 nm, 396 nm or 399 nm, etc.

[0049] In some examples, the first light ray used in the first photothermal annealing treatment may be infrared light, and the second light ray used in the second photothermal annealing treatment may be ultraviolet light.

[0050] It should be emphasized that the surfaces of the cell body 100 irradiated by the first photothermal annealing treatment and the second photothermal annealing treatment may be only partially the same, completely the same or completely different. The following will describe various irradiation situations in detail.

[0051] In some embodiments, the step of performing the first photothermal annealing treatment at least includes irradiating the first surface 111 with a first light beam. In other words, the first light beam may irradiate only the first surface 111, or may irradiate both the first surface 111 and the second surface 121 simultaneously.

[0052] In some embodiments, referring to Figure 1 or Figure 2 , at least a part of the surface of the second surface 121 is a polished surface, and the step of performing the second photothermal annealing treatment at least includes irradiating the second surface 121 with a second light beam. In other words, the second light beam may irradiate only the second surface 121, or may irradiate both the second surface 121 and the first surface 111 simultaneously. It should be emphasized that at least a part of the surface of the second surface 121 being a polished surface is beneficial to improving the uniformity of the second alumina layer 103 formed on the second surface 121, thereby being beneficial to balancing the passivation effect of each region in the second alumina layer 103 on the substrate 101 after being irradiated by the second light beam. For example, the content of hydrogen ions in each region of the second alumina layer 103 after being irradiated by the second light beam is increased almost uniformly, so that each region in the second alumina layer 103 has a good passivation effect on the substrate 101. It should be noted that Figure 1 and Figure 2 both take the entire surface of the second surface 121 as a polished surface as an example. In practical applications, only the region of the second surface facing the electrode may be a polished surface, and the region not covered by the electrode may be a matte surface or have other surface texture structures to enhance the absorption effect of the second surface on incident light and increase the photoelectric conversion efficiency of the photovoltaic cell.

[0053] In other embodiments, the first light beam may also irradiate only the second surface, and / or the second light beam may also irradiate only the first surface.

[0054] In some embodiments, referring to Figure 1 or Figure 2 , the first surface 111 may be a matte surface, which can improve the absorption utilization rate of the first surface 111 for incident light. In some examples, the matte surface may be a pyramid matte surface. As a common matte surface, the pyramid matte surface not only reduces the reflectivity of the first surface, but also forms a light trap, enhances the absorption effect of the first surface on incident light, and increases the photoelectric conversion efficiency of the photovoltaic cell.

[0055] It should be noted that, in some embodiments, the cell body 100 is a single-sided cell. The first side 111 can be regarded as the front side of the cell body 100, that is, the first side 111 can be used as the light-receiving surface for receiving incident light, and the second side 121 can be used as the backlight surface. In other embodiments, the cell body 100 is a double-sided cell, then both the first side 111 and the second side 121 can be used as the light-receiving surfaces and can be used to receive incident light. It can be understood that the backlight surface described in an embodiment of the present disclosure can also receive incident light, but the degree of receiving incident light is weaker than that of the light-receiving surface, so it is defined as the backlight surface.

[0056] It should be noted that, for the second photothermal annealing treatment, compared with the improvement effect on the passivation effect of the substrate 101 after irradiating only the second side 121 with the second light, the improvement effect on the passivation effect of the substrate 101 after irradiating both the first side 111 and the second side 121 with the second light is better; compared with the improvement effect on the passivation effect of the substrate 101 after irradiating only the first side 111 with the second light, the improvement effect on the passivation effect of the substrate 101 after irradiating the second side 121 with the second light is better.

[0057] In some embodiments, the steps of performing the first photothermal annealing treatment may include: providing a first light source and a second light source, the first light source is used to irradiate the first side 111, the second light source is used to irradiate the second side 121, and the first light includes a first sub-light provided by the first light source and a second sub-light provided by the second light source. In some examples, the first light source and the second light source may be respectively located on opposite sides of the cell body 100 in the thickness direction, that is, the first light source is located on the side of the first side 111 away from the second side 121, and the second light source is located on the side of the second side 121 away from the first side 111.

[0058] In some embodiments, the steps of performing the second photothermal annealing treatment may include: providing a third light source and a fourth light source, the third light source is used to irradiate the first side 111, the fourth light source is used to irradiate the second side 121, and the second light includes a third sub-light provided by the third light source and a fourth sub-light provided by the fourth light source. In some examples, the third light source and the fourth light source may be respectively located on opposite sides of the cell body 100 in the thickness direction, that is, the third light source is located on the side of the first side 111 away from the second side 121, and the fourth light source is located on the side of the second side 121 away from the first side 111.

[0059] It should be noted that when the first light source and the second light source are provided simultaneously during the first photothermal annealing treatment, during the second photothermal annealing treatment, the third light source and the fourth light source can be provided simultaneously or only one of the third light source and the fourth light source can be provided; when only one of the first light source and the second light source is provided during the first photothermal annealing treatment, during the second photothermal annealing treatment, the third light source and the fourth light source can be provided simultaneously or only one of the third light source and the fourth light source can be provided.

[0060] In some examples, the operating parameters of the first light source and the second light source, such as the light wavelength, light intensity density, and irradiation time, etc., can be respectively the same, so that the photothermal annealing environments constructed by the first photothermal annealing treatment for the first surface 111 and the second surface 121 are the same; in other examples, at least one of the light wavelength, light intensity density, and irradiation time provided by the first light source and the second light source can be different, so that the photothermal annealing environments constructed by the first photothermal annealing treatment for the first surface 111 and the second surface 121 are different.

[0061] In some examples, the operating parameters of the third light source and the fourth light source, such as the light wavelength, light intensity density, and irradiation time, etc., can be respectively the same, so that the photothermal annealing environments constructed by the second photothermal annealing treatment for the first surface 111 and the second surface 121 are the same; in other examples, at least one of the light wavelength, light intensity density, and irradiation time provided by the third light source and the fourth light source is different, so that the photothermal annealing environments constructed by the second photothermal annealing treatment for the first surface 111 and the second surface 121 are different.

[0062] The design of the operating parameters of the first light source, the second light source, the third light source, and the fourth light source will be described in detail below.

[0063] In some examples, the light intensity density provided by the first light source can be less than the light intensity density provided by the second light source. In other words, the irradiation intensity of the first sub-ray on the first surface 111 is lower than the irradiation intensity of the second sub-ray on the second surface 121, which is beneficial to making the photon energy received per unit area on the second surface 121 higher than the photon energy received per unit area on the first surface 111.

[0064] It should be noted that compared with the first surface 111 as the light-receiving surface, the second surface 121, which is generally the backlight surface, has a relatively low light utilization rate. For example, there can also be a polysilicon layer between the substrate 101 and the second alumina layer 103, and the polysilicon layer will reduce the absorption of photon energy by the substrate 101. Therefore, designing the light intensity density provided by the first light source to be less than the light intensity density provided by the second light source is beneficial to compensating for the problem of the relatively low light utilization rate of the second surface 121 in the step of the first photothermal annealing to ensure a good passivation effect of the second light source on the second surface 121.

[0065] In some examples, the light intensity density provided by the third light source can be less than that provided by the fourth light source. In other words, the irradiation intensity of the third sub-ray on the first surface 111 is lower than that of the fourth sub-ray on the second surface 121, which is beneficial to making the photon energy received per unit area on the second surface 121 higher than that received per unit area on the first surface 111.

[0066] It should be noted that compared with the first surface 111 as the light-receiving surface, the second surface 121, generally as the backlight surface, has a relatively low light utilization rate. For example, there may also be a polysilicon layer between the substrate 101 and the second alumina layer 103, and the polysilicon layer will reduce the absorption of photon energy by the substrate 101. Therefore, designing the light intensity density provided by the third light source to be less than that provided by the fourth light source is beneficial to compensating for the problem of the low light utilization rate of the second surface 121 in the second photo-thermal annealing step to ensure a good passivation effect of the fourth light source on the second surface 121.

[0067] It is worth noting that in practical applications, when the light intensity density provided by the first light source is less than that provided by the second light source, the light intensity density provided by the third light source can be less than, equal to, or greater than that provided by the fourth light source; when the light intensity density provided by the third light source is less than that provided by the fourth light source, the light intensity density provided by the first light source can be less than, equal to, or greater than that provided by the second light source. In other words, the magnitude relationship between the light intensity densities provided by the first light source and the second light source and the magnitude relationship between the light intensity densities provided by the third light source and the fourth light source can be flexibly adjusted according to specific requirements.

[0068] In one example, in the step of the first photo-thermal annealing treatment, when irradiating both the first surface 111 and the second surface 121, the light intensity density provided by the first light source can be 4 kW / m 2 ~8 kW / m 2 , for example, it can be 4.5 kW / m 2 , 5 kW / m 2 , 5.5 kW / m 2 , 6 kW / m 2 , 6.5 kW / m 2 , 7 kW / m 2 or 7.5 kW / m 2 etc.; the light intensity density provided by the second light source can be 10 kW / m 2 ~18 kW / m 2 , for example, it can be 10.5 kW / m 2 , 11 kW / m 2 , 11.5 kW / m 2 , 12 kW / m 2 , 12.5 kW / m 2 , 13 kW / m2 , 13.5 kW / m 2 , 14 kW / m 2 , 14.5 kW / m 2 , 15 kW / m 2 , 15.5 kW / m 2 , 16 kW / m 2 , 16.5 kW / m 2 , 17 kW / m 2 or 17.5 kW / m 2 etc.

[0069] In one example, in the steps of the second photothermal annealing treatment, when irradiating both the first surface 111 and the second surface 121, the light intensity density provided by the third light source can be 4 kW / m 2 ~8 kW / m 2 , for example, it can be 4.5 kW / m 2 , 5 kW / m 2 , 5.5 kW / m 2 , 6 kW / m 2 , 6.5 kW / m 2 , 7 kW / m 2 or 7.5 kW / m 2 etc.; the light intensity density provided by the fourth light source can be 10 kW / m 2 ~18 kW / m 2 , for example, it can be 10.5 kW / m 2 , 11 kW / m 2 , 11.5 kW / m 2 , 12 kW / m 2 , 12.5 kW / m 2 , 13 kW / m 2 , 13.5 kW / m 2 , 14 kW / m 2 , 14.5 kW / m 2 , 15 kW / m 2 , 15.5 kW / m 2 , 16 kW / m 2 , 16.5 kW / m 2 , 17 kW / m 2 or 17.5 kW / m 2 etc.

[0070] In some embodiments, when only irradiating the first surface 111 in the steps of the first photothermal annealing treatment and irradiating at least one of the first surface 111 and the second surface 121 in the steps of the second photothermal annealing treatment, the light intensity density of the first light ray can be 10 kW / m 2 ~20 kW / m 2, the light intensity density of the second light beam is 6 kW / m 2 ~18 kW / m 2 . It should be noted that the first light beam only includes the first sub-light beam for irradiating the first surface 111, and the second light beam includes at least one of the third sub-light beam for irradiating the first surface 111 and the fourth sub-light beam for irradiating the second surface 121, and the light intensity densities of the third sub-light beam and the fourth sub-light beam can both be 6 kW / m 2 ~18 kW / m 2 .

[0071] In some examples, the light intensity density of the first light beam can be 10.5 kW / m 2 , 11 kW / m 2 , 11.5 kW / m 2 , 12 kW / m 2 , 12.5 kW / m 2 , 13 kW / m 2 , 13.5 kW / m 2 , 14 kW / m 2 , 14.5 kW / m 2 , 15 kW / m 2 , 15.5 kW / m 2 , 16 kW / m 2 , 16.5 kW / m 2 , 17 kW / m 2 , 17.5 kW / m 2 , 18 kW / m 2 , 18.5 kW / m 2 , 19 kW / m 2 or 19.5 kW / m 2 etc.

[0072] In some examples, the light intensity density of the second light beam can be 6.5 kW / m 2 , 7 kW / m 2 , 10.5 kW / m 2 , 7.5 kW / m 2 , 8 kW / m 2 , 8.5 kW / m 2 , 9 kW / m 2 , 9.5 kW / m 2 , 10 kW / m 2 , 10.5 kW / m 2 , 11 kW / m 2 , 11.5 kW / m 2 , 12 kW / m 2 , 12.5 kW / m 2 , 13 kW / m 2 , 13.5 kW / m2 、 14 kW / m 2 、 14.5 kW / m 2 、 15 kW / m 2 、 15.5 kW / m 2 、 16 kW / m 2 、 16.5 kW / m 2 、 17 kW / m 2 or 17.5 kW / m 2 etc.

[0073] In some examples, the processing duration of the first photothermal annealing treatment can be 30 s to 50 s. For example, it can be 31 s, 32 s, 33 s, 34 s, 35 s, 36 s, 37 s, 38 s, 39 s, 40 s, 41 s, 42 s, 43 s, 44 s, 45 s, 46 s, 47 s, 48 s or 49 s, etc.; the processing duration of the second photothermal annealing treatment is 2 s to 15 s. For example, it can be 3 s, 4 s, 5 s, 6 s, 7 s, 8 s, 9 s, 10 s, 11 s, 12 s, 13 s or 14 s, etc.

[0074] In some examples, when only the first surface 111 is irradiated in the step of the first photothermal annealing treatment and only the second surface 121 is irradiated in the step of the second photothermal annealing treatment, the processing duration of the first photothermal annealing treatment can be 30 s to 50 s, and the processing duration of the second photothermal annealing treatment is 8 s to 15 s.

[0075] In some other examples, when only the first surface 111 is irradiated in the step of the first photothermal annealing treatment and only the first surface 111 is irradiated in the step of the second photothermal annealing treatment, the processing duration of the first photothermal annealing treatment can be 30 s to 50 s, and the processing duration of the second photothermal annealing treatment is 3 s to 7 s.

[0076] In still some other examples, when only the first surface 111 is irradiated in the step of the first photothermal annealing treatment and both the first surface 111 and the second surface 121 are irradiated in the step of the second photothermal annealing treatment, the processing duration of the first photothermal annealing treatment can be 30 s to 50 s, and the processing duration of the second photothermal annealing treatment is 6 s to 10 s.

[0077] In the above various embodiments, the heating temperature of the first photothermal annealing treatment can be greater than the heating temperature of the second photothermal annealing treatment. It should be noted that within a certain range, the higher the heating temperature of the photothermal annealing treatment, the more conducive it is to the diffusion of ions that can achieve a passivation effect towards the substrate 101, so as to increase the probability that the surface defects of the substrate 101 are passivated by ions. Based on this, designing the heating temperature of the first photothermal annealing treatment to be greater than the heating temperature of the second photothermal annealing treatment is conducive to making the passivation effect of the substrate 101 better by means of the first photothermal annealing treatment, while controlling the heating temperature of the second photothermal annealing treatment to be lower, so as to shorten the cooling time, which is convenient for subsequent timely IV (current-voltage) testing of the prepared photovoltaic cell, thereby facilitating the shortening of the equipment length required for manufacturing the photovoltaic cell and improving the service life of the transmission belt.

[0078] In one example, the heating temperature of the first photothermal annealing treatment can be 240°C to 300°C. For example, it can be 245°C, 250°C, 255°C, 260°C, 265°C, 270°C, 275°C, 280°C, 285°C, 290°C or 295°C, etc.; the heating temperature of the second photothermal annealing treatment can be 50°C to 140°C. For example, it can be 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, 95°C, 100°C, 105°C, 110°C, 115°C, 120°C, 125°C, 130°C or 135°C, etc.

[0079] In the above various embodiments, the step of performing the first photothermal annealing treatment can include: controlling the light intensity density of the first light to gradually change within the treatment duration of the first photothermal annealing treatment, and / or, controlling the heating temperature of the first photothermal annealing treatment to gradually change within the treatment duration of the first photothermal annealing treatment.

[0080] It should be noted that controlling the light intensity density of the first light to gradually change within the treatment duration of the first photothermal annealing treatment can include the following three situations: as the first photothermal annealing treatment progresses, the light intensity density of the first light gradually decreases, gradually increases, first gradually decreases and then gradually increases, or first gradually increases and then gradually decreases. Controlling the heating temperature of the first photothermal annealing treatment to gradually change within the treatment duration of the first photothermal annealing treatment can include the following three situations: as the first photothermal annealing treatment progresses, the heating temperature of the first photothermal annealing treatment gradually decreases, gradually increases, first gradually decreases and then gradually increases, or first gradually increases and then gradually decreases. In this way, it is conducive to controlling the temperature on the surface of the photovoltaic cell and not easily causing the phenomenon that pollutants on the transmission belt adhere to the surface of the photovoltaic cell.

[0081] Among them, controlling the light intensity density of the first light ray to gradually decrease, or to first gradually increase and then gradually decrease, or the heating temperature of the first photothermal annealing treatment to gradually decrease, or to first gradually increase and then gradually decrease, is conducive to shortening the cooling time, so as to facilitate subsequent timely IV (current-voltage) testing of the prepared photovoltaic cell, thereby facilitating the shortening of the equipment length required for preparing the photovoltaic cell and improving the service life of the transmission belt.

[0082] In the above various embodiments, the step of performing the second photothermal annealing treatment may include: controlling the light intensity density of the second light ray to gradually change within the treatment duration of the second photothermal annealing treatment, and / or controlling the heating temperature of the second photothermal annealing treatment to gradually change within the treatment duration of the second photothermal annealing treatment.

[0083] It should be noted that controlling the light intensity density of the second light ray to gradually change within the treatment duration of the second photothermal annealing treatment may include the following three situations: as the second photothermal annealing treatment progresses, the light intensity density of the second light ray gradually decreases, gradually increases, first gradually decreases and then gradually increases, or first gradually increases and then gradually decreases. Controlling the heating temperature of the second photothermal annealing treatment to gradually change within the treatment duration of the second photothermal annealing treatment may include the following three situations: as the second photothermal annealing treatment progresses, the heating temperature of the second photothermal annealing treatment gradually decreases, gradually increases, first gradually decreases and then gradually increases, or first gradually increases and then gradually decreases. In this way, it is conducive to making the temperature on the surface of the photovoltaic cell controllable and not easily causing the phenomenon that the pollutants on the transmission belt adhere to the surface of the photovoltaic cell.

[0084] Among them, controlling the light intensity density of the second light ray to gradually decrease, or to first gradually increase and then gradually decrease, or the heating temperature of the second photothermal annealing treatment to gradually decrease, or to first gradually increase and then gradually decrease, is conducive to shortening the cooling time, so as to facilitate subsequent timely IV (current-voltage) testing of the prepared photovoltaic cell, thereby facilitating the shortening of the equipment length required for preparing the photovoltaic cell and improving the service life of the transmission belt.

[0085] In some embodiments, the method for controlling the light intensity density of the first light ray to gradually change within the treatment duration of the first photothermal annealing treatment includes: designing at least one of the first light source or the second light source to include a plurality of lamp groups connected in series in sequence, and adopting power control to gradually change the light intensity of the plurality of lamp groups; the method for controlling the light intensity density of the second light ray to gradually change within the treatment duration of the second photothermal annealing treatment includes: designing at least one of the third light source or the fourth light source to include a plurality of lamp groups connected in series in sequence, and adopting power control to gradually change the light intensity of the plurality of lamp groups.

[0086] In some embodiments, the laser-enhanced contact treatment can be a laser-assisted sintering technique, also known as laser-enhanced contact optimization, which is used to improve the contact between the electrodes and the silicon wafer in a photovoltaic cell. In the laser-enhanced contact treatment, a laser is used for non-destructive carrier injection. After the laser-enhanced contact treatment, the contact resistance between the electrodes and the silicon wafer in the photovoltaic cell is significantly reduced, which is beneficial to increasing the open-circuit voltage and short-circuit current of the photovoltaic cell.

[0087] In summary, on the one hand, compared with the second light used in the second photothermal annealing treatment, the wavelength of the first light used in the first photothermal annealing treatment is larger, so the photon energy of the first light is greater, which is beneficial to the deep activation of the first alumina layer 102 and / or the second alumina layer 103. For example, it can increase the content of hydrogen ions in the first alumina layer 102 and / or the second alumina layer 103 to improve the passivation effect of the first alumina layer 102 and / or the second alumina layer 103 on the surface of the substrate 101. On the other hand, compared with the first light used in the first photothermal annealing treatment, the wavelength of the second light used in the second photothermal annealing treatment is smaller. The second light is not sufficient to break the silicon-hydrogen bonds on the surface of the substrate 101. The second light is incident on the shallow surface of the photovoltaic cell to perform secondary activation on the first alumina layer 102 and / or the second alumina layer 103, which is beneficial to improving the contact performance between the electrode and the substrate 101. For example, it can reduce the probability of metal recombination between the electrode and the substrate 101. On the other hand, performing the first photoannealing treatment and the second photoannealing treatment at intervals before and after the laser-enhanced contact treatment is beneficial to increasing the lifetime of minority carriers. In this way, the combined action of multiple aspects is beneficial to improving the photoelectric conversion efficiency of the finally prepared photovoltaic cell.

[0088] Another embodiment of the present disclosure also provides a photovoltaic cell prepared by the preparation method provided in the foregoing embodiment. The following will describe in detail the photovoltaic cell provided in another embodiment of the present disclosure with reference to the accompanying drawings. It should be noted that the same or corresponding parts as those in the foregoing embodiment will not be described in detail here.

[0089] Reference Figure 1 or Figure 2 , the photovoltaic cell includes: a photovoltaic cell formed according to the preparation method provided in the foregoing embodiment.

[0090] It should be noted that the photovoltaic cell can be a cell with a passivation structure such as a TOPCON cell, a PERC cell, an IBC cell, or a heterojunction cell. Forming a photovoltaic cell according to the preparation method provided in the foregoing embodiment and performing the first photoannealing treatment and the second photoannealing treatment at intervals before and after the laser-enhanced contact treatment are beneficial to improving the photoelectric conversion efficiency of the formed photovoltaic cell.

[0091] Those of ordinary skill in the art can understand that the above-described embodiments are specific examples for implementing the present disclosure. In actual applications, various changes can be made to them in form and details without departing from the spirit and scope of the embodiments of the present disclosure. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the embodiments of the present disclosure. Therefore, the protection scope of the embodiments of the present disclosure should be subject to the scope defined by the claims.

Claims

1. A method for preparing a photovoltaic cell, characterized in that: include: Providing a cell body, the cell body comprising a substrate having a first surface and a second surface opposite to each other, a first aluminum oxide layer located on the first surface, and a second aluminum oxide layer located on the second surface; Using a first light to irradiate at least one of the first surface and the second surface to perform a first photothermal annealing treatment on the cell body; Then, the battery cell body is subjected to laser enhanced contact processing; Using a second light to irradiate at least one of the first surface and the second surface to perform a second photothermal annealing treatment on the cell body, and at least one of the first aluminum oxide layer and the second aluminum oxide layer is irradiated by both the first light and the second light; Wherein, the wavelength of the first light is greater than the wavelength of the second light.

2. The method for preparing a photovoltaic cell according to claim 1, characterized in that: The step of performing the first photothermal annealing treatment at least includes irradiating the first surface with the first light; and / or, at least a portion of the surface of the second surface is a polished surface, and the step of performing the second photothermal annealing treatment at least includes irradiating the second surface with the second light.

3. The method for preparing a photovoltaic cell according to claim 1, characterized in that: The step of performing the first photothermal annealing treatment includes: providing a first light source and a second light source, the first light source is used to irradiate the first surface, the second light source is used to irradiate the second surface, the first light includes a first sub-light provided by the first light source and a second sub-light provided by the second light source; and / or, The step of performing the second photothermal annealing treatment includes: providing a third light source and a fourth light source, the third light source is used to irradiate the first surface, the fourth light source is used to irradiate the second surface, and the second light includes a third sub-light provided by the third light source and a fourth sub-light provided by the fourth light source.

4. The method for preparing a photovoltaic cell according to claim 3, characterized in that: The first light source and the second light source provide light with at least one of a different wavelength, light intensity density and irradiation time; and / or the third light source and the fourth light source provide light with at least one of a different wavelength, light intensity density and irradiation time.

5. The method for preparing a photovoltaic cell according to claim 4, characterized in that: The light intensity density provided by the first light source is smaller than the light intensity density provided by the second light source; and / or the light intensity density provided by the third light source is smaller than the light intensity density provided by the fourth light source.

6. The method for preparing a photovoltaic cell according to claim 5, characterized in that: The light intensity density provided by the first light source is 4kW / m 2 ~8kW / m 2 The light intensity density provided by the second light source is 10kW / m 2 ~18kW / m 2 .

7. The method for preparing a photovoltaic cell according to claim 1, characterized in that: The step of providing the battery cell body also includes: forming a first passivation layer on a side of the first aluminum oxide layer away from the first surface; and / or, forming a second passivation layer on a side of the second aluminum oxide layer away from the second surface; The first passivation layer and / or the second passivation layer includes at least one of a silicon nitride layer, a silicon oxynitride layer or a silicon oxide layer.

8. The method for preparing a photovoltaic cell according to any one of claims 1 to 7, characterized in that: The wavelength of the first light is 800nm~1000nm, and the wavelength of the second light is 365nm~400nm.

9. The method for preparing a photovoltaic cell according to any one of claims 1 to 7, characterized in that: The heating temperature of the first photothermal annealing treatment is greater than the heating temperature of the second photothermal annealing treatment.

10. A photovoltaic cell, characterized in that: include: A photovoltaic cell formed by the method for preparing a photovoltaic cell according to any one of claims 1 to 9.

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