Photovoltaic cell and preparation method thereof

Abstract

The embodiment of the invention relates to the photovoltaic field, and provides a photovoltaic cell and a preparation method thereof, and the preparation method comprises the steps: providing a cell piece body which comprises a substrate with 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; irradiating at least one of the first surface and the second surface with first light so as to carry out first photo-thermal annealing treatment on the battery piece body; carrying out laser enhanced contact processing on the battery piece body; irradiating at least one of the first surface and the second surface with second light to perform second photo-thermal annealing treatment on the battery piece body; wherein the wavelength of the first light is greater than that of the second light. The embodiment of the invention is at least beneficial to improving the photoelectric conversion efficiency of the photovoltaic cell.

Description

Technical Field

[0001] The present disclosure relates to the photovoltaic field, and in particular to a photovoltaic cell and a preparation method thereof. Background Art

[0002] As fossil energy is gradually depleted, photovoltaic cells are becoming more and more widely used as a new energy alternative. Photovoltaic cells are devices that convert sunlight into electrical energy. Photovoltaic cells use the principle of photovoltaics to generate carriers, and then use electrodes to lead the carriers out, thereby facilitating the effective use of electrical energy.

[0003] Current photovoltaic cells mainly include IBC cells (Interdigitated Back Contact), TOPCON (Tunnel Oxide Passivated Contact), PERC cells (Passivated emitter and real cell) and heterojunction cells.

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

[0005] The embodiments of the present disclosure provide a photovoltaic cell and a method for preparing the same, which are at least beneficial to improving the photoelectric conversion efficiency of the photovoltaic cell.

[0006] According to some embodiments of the present disclosure, on the one hand, the embodiments of the present disclosure provide a method for preparing a photovoltaic cell, comprising: providing a cell body, the cell body comprising a substrate having a first surface and a second surface relative 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 performing a laser enhanced contact treatment on the cell body; 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; wherein the wavelength of the first light is greater than the wavelength of the second light.

[0007] In some embodiments, 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.

[0008] In some embodiments, 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, 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.

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

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

[0012] In some embodiments, 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; wherein 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 is 800nm-1000nm, and the wavelength of the second light is 365nm-400nm.

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

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

[0016] The technical solution provided by the embodiments of the present disclosure has at least the following advantages: 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, and the photon energy of the first light is larger, which is conducive to deep activation of the first aluminum oxide layer and / or the second aluminum oxide layer, for example, increasing 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 enough to break the silicon-hydrogen bond on the surface of the substrate. The second light is incident on the shallow surface of the photovoltaic cell, and the first aluminum oxide layer and / or the second aluminum oxide layer are secondary activated, which is conducive to improving the contact performance between the electrode and the substrate, for example, reducing the metal recombination probability between the electrode and the substrate; on the other hand, the first photoannealing treatment and the second photoannealing treatment are performed at intervals before and after the laser enhanced contact treatment, which is conducive to improving the life of minority carriers. In this way, the combined effect of multiple aspects is conducive to improving the photoelectric conversion efficiency of the photovoltaic cell finally prepared. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] One or more embodiments are exemplarily illustrated by pictures in the corresponding drawings, and these exemplified descriptions do not constitute a limitation on the embodiments. Unless otherwise specified, the pictures in the drawings do not constitute a scale limitation. In order to more clearly illustrate the embodiments of the present disclosure or the technical solutions in the traditional technology, the drawings required for use in the embodiments are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present disclosure. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0018] Figure 1 A schematic diagram of a partial cross-sectional structure of a cell body in a method for preparing a photovoltaic cell provided in an embodiment of the present disclosure; Figure 2 Another partial cross-sectional structural schematic diagram of a cell body in a method for preparing a photovoltaic cell provided in an embodiment of the present disclosure. DETAILED DESCRIPTION

[0019] As known from the background technology, the photoelectric conversion efficiency of photovoltaic cells needs to be improved.

[0020] The present disclosure provides a photovoltaic cell and a preparation method thereof. In the preparation method, on the one hand, the wavelength of the first light used in the first photothermal annealing treatment is larger than that of the second light used in the second photothermal annealing treatment, so the photon energy of the first light is larger, which is conducive to deep activation of the first aluminum oxide layer and / or the second aluminum oxide layer, for example, increasing 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 enough to break the silicon-hydrogen bond on the surface of the substrate. The second light is incident on the shallow surface of the photovoltaic cell, and the first aluminum oxide layer and / or the second aluminum oxide layer are secondary activated, which is conducive to improving the contact performance between the electrode and the substrate, for example, reducing the metal recombination probability between the electrode and the substrate; on the other hand, the first photoannealing treatment and the second photoannealing treatment are performed at intervals before and after the laser enhanced contact treatment, which is conducive to improving the life of minority carriers. In this way, the combined effect of multiple aspects is conducive to improving the photoelectric conversion efficiency of the photovoltaic cell finally prepared.

[0021] In the description of the embodiments of the present disclosure, the technical terms "first", "second", etc. are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features. In the description of the embodiments of the present disclosure, the meaning of "multiple" is more than two, unless otherwise clearly and specifically defined.

[0022] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present disclosure. The appearance of the phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0023] In the description of the embodiments of the present disclosure, the term "and / or" is only a description of the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B may represent: A exists, A and B exist at the same time, and B exists. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0024] In the description of the embodiments of the present disclosure, the term "multiple" refers to more than two (including two). Similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple pieces" refers to more than two pieces (including two pieces).

[0025] In the description of the embodiments of the present disclosure, the orientations or positional relationships indicated by technical terms such as "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", and "circumferential" are based on the orientations or positional relationships shown in the accompanying drawings and are only for the convenience of describing the embodiments of the present disclosure and simplifying the description. They do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the embodiments of the present disclosure.

[0026] In the description of the embodiments of the present disclosure, unless otherwise clearly specified and limited, technical terms such as "installed", "connected", "connected", "fixed" and the like 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 mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, and it can be the internal connection of 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 the specific circumstances.

[0027] In the accompanying drawings corresponding to the embodiments of the present disclosure, the thickness and area of ​​the layers are exaggerated for better understanding and ease of description. When describing a component (such as a layer, film, region or substrate) on another component or on the surface of another component, the component may be "directly" located on the surface of the other component, or a third component may exist 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 as being "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 is it formed on a partial edge of the entire surface.

[0028] In the description of the embodiments of the present disclosure, when a component "includes" another component, unless otherwise specified, other components are not excluded, and other components may be further included. In addition, when a component such as a layer, film, region, or plate is referred to as being "on / located on" another component, it may be "directly on" the other component (i.e., located on the surface of the other component with no other components between them), or another component may exist in between. 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 no other components are located in between.

[0029] The terms used in the description of the various embodiments described herein are only used to describe specific embodiments and are not intended to be limiting. As used in the description of the various embodiments described and in the appended claims, "the components" are also intended to include plural forms unless the context clearly indicates otherwise. Among them, components include components such as layers, films, regions, or plates.

[0030] The following will describe the various embodiments of the present disclosure in detail with reference to the accompanying drawings. However, it will be appreciated by those skilled in the art that in the various embodiments of the present disclosure, many technical details are provided in order to enable the reader to 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 be implemented.

[0031] An embodiment of the present disclosure provides a method for preparing a photovoltaic cell. The method for preparing a photovoltaic cell provided by an embodiment of the present disclosure will be described in detail below with reference to the accompanying drawings.

[0032] refer to Figure 1 or Figure 2 The preparation method of a photovoltaic cell includes the following steps: providing a cell body 100, the cell body 100 including a substrate 101 having a first surface 111 and a second surface 121 opposite to each other, 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; using a first light to irradiate at least one of the first surface 111 and the second surface 121 to perform a first photothermal annealing treatment on the cell body 100; then performing a laser enhanced contact treatment on the cell body 100; using a second light to irradiate at least one of the first surface 111 and the second surface 121 to perform a second photothermal annealing treatment on the cell body 100; wherein the wavelength of the first light is greater than the wavelength of the second light.

[0033] in, Figure 1 A schematic diagram of a partial cross-sectional structure of a cell body in a method for preparing a photovoltaic cell provided in an embodiment of the present disclosure; Figure 2 Another partial cross-sectional structural schematic diagram of a cell body in a method for preparing a photovoltaic cell provided in an embodiment of the present disclosure.

[0034] It is worth noting 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, and the photon energy of the first light is larger, which is conducive to deep activation of the first aluminum oxide layer 102 and / or the second aluminum oxide layer 103, such as increasing the content of hydrogen ions in the first aluminum oxide layer 102 and / or the second aluminum oxide layer 103, so as to improve the passivation effect of the first aluminum oxide layer 102 and / or the second aluminum oxide layer 103 on the surface of the substrate 101, such as increasing the probability 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 enough to break the silicon-hydrogen bond on the surface of the substrate 101. The second light is incident on the shallow surface of the photovoltaic cell, and the first aluminum oxide layer 102 and / or the second aluminum oxide layer 103 are activated for the second time, which is beneficial to improve the contact performance between the electrode and the substrate 101, such as reducing the metal recombination probability between the electrode and the substrate 101; on the other hand, the first photoannealing treatment and the second photoannealing treatment are carried out before and after the laser enhanced contact treatment, which is beneficial to improve the life of minority carriers. In this way, the combined effect of multiple aspects is beneficial to improve the photoelectric conversion efficiency of the photovoltaic cell finally prepared.

[0035] In some examples, the photoelectric conversion efficiency of a photovoltaic cell formed using the photovoltaic cell preparation method provided by an embodiment of the present disclosure can be increased by about 0.03% to 0.05%.

[0036] The following is a detailed description of each step in the method for preparing a photovoltaic cell provided in an embodiment of the present disclosure: In some embodiments, reference Figure 2 The step of providing the battery cell body 100 may also include: forming a first passivation layer 104 on a side of the first aluminum oxide layer 102 away from the first surface 111; and / or, forming a second passivation layer 105 on a side of the second aluminum oxide 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.

[0037] It is worth emphasizing that the first photothermal annealing treatment and the second photothermal annealing treatment can respectively activate the first aluminum oxide layer 102 and / or the second aluminum oxide layer 103 to enhance the passivation effect of the first aluminum oxide layer 102 and / or the second aluminum oxide 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, to enhance the content of ions that can play a passivation effect in the first passivation layer 104 and / or the second passivation layer 105, thereby further enhancing the probability that the surface defects of the substrate 101 are passivated by ions, thereby enhancing the overall passivation effect of the photovoltaic cell.

[0038] It should be noted that Figure 2 In the example, a first passivation layer 104 is formed on the side of the first aluminum oxide layer 102 away from the first surface 111, and a second passivation layer 105 is formed on the side of the second aluminum oxide layer 103 away from the second surface 121. In actual applications, the first passivation layer may be formed only on the side of the first aluminum oxide layer away from the first surface, or the second passivation layer may be formed only on the side of the second aluminum oxide layer away from the second surface.

[0039] In some embodiments, the step of providing the cell body 100 may further include: disposing electrode slurry on the cell body 100; and performing electrode metallization treatment on the electrode slurry to form an electrode on at least one of the first surface 111 and the second surface 121 (not shown in the figure).

[0040] In some examples, the step of disposing the electrode paste on the cell body 100 may include: disposing the electrode paste on the cell body 100 by screen printing, or disposing the electrode paste on the cell body 100 by electroplating. In some examples, the electrode paste may include at least one of silver, aluminum, copper, tin, gold, lead, or nickel.

[0041] In some examples, the step of performing electrode metallization treatment on the electrode slurry may include: performing a sintering process on the electrode slurry. In some examples, the electrode slurry contains a material with a highly corrosive component such as glass, so that during the sintering process, the corrosive component will corrode the first aluminum oxide layer 102 and the first passivation layer 104, so that the final electrode is embedded in the first aluminum oxide layer 102 and the first passivation layer 104; and / or, during the sintering process, the corrosive component will corrode the second aluminum oxide layer 103 and the second passivation layer 105, so that the final electrode is embedded in the second aluminum oxide layer 103 and the second passivation layer 105.

[0042] 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. The elemental semiconductor material may be in a single crystalline state, a polycrystalline state, an amorphous state, or a microcrystalline state (a state having both a single crystalline state and an amorphous state is referred to as a microcrystalline state), for example, silicon may be at least one of single crystalline silicon, polycrystalline silicon, amorphous silicon, or microcrystalline silicon.

[0043] 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 germanium, silicon carbide, gallium arsenide, indium gallium, perovskite, cadmium telluride, copper indium selenide and other materials.

[0044] 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 an N-type doping element, which may be at least one of the V-group elements such as phosphorus (P), bismuth (Bi), antimony (Sb), or arsenic (As). The P-type semiconductor substrate is doped with a P-type element, which may be at least one of the III-group elements such as boron (B), aluminum (Al), gallium (Ga), or gallium (In).

[0045] In some embodiments, the wavelength of the first light used in the first photothermal annealing treatment may be 800nm~1000nm, for example, the wavelength of the first light may be 810nm, 820nm, 830nm, 840nm, 850nm, 860nm, 870nm, 880nm, 890nm, 900nm, 910nm, 920nm, 930nm, 940nm, 950nm, 960nm, 970nm, 980nm or 990nm, etc.; the wavelength of the second light used in the second photothermal annealing treatment may be 365nm~400nm, for example, the wavelength of the second light may be 370nm, 372nm, 375nm, 376nm, 378nm, 380nm, 383nm, 385nm, 386nm, 390nm, 392nm, 395nm, 396nm or 399nm, etc.

[0046] In some examples, the first light used in the first photothermal annealing process may be infrared light, and the second light used in the second photothermal annealing process may be ultraviolet light.

[0047] It is worth emphasizing 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. Various irradiation situations are described in detail below.

[0048] In some embodiments, the step of performing the first photothermal annealing treatment at least includes using the first light to irradiate the first surface 111. In other words, the first light can irradiate only the first surface 111, or can irradiate the first surface 111 and the second surface 121 at the same time.

[0049] In some embodiments, reference Figure 1 or Figure 2 , at least 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. In other words, the second light can irradiate only the second surface 121, or can irradiate the second surface 121 and the first surface 111 at the same time. It is worth emphasizing that at least part of the surface of the second surface 121 is a polished surface, which is beneficial to improving the uniformity of the second aluminum oxide layer 103 formed on the second surface 121, thereby balancing the passivation effect of each region in the second aluminum oxide layer 103 after irradiation with the second light on the substrate 101, for example, the content of hydrogen ions in each region of the second aluminum oxide layer 103 after irradiation with the second light is almost uniformly increased, so that each region of the second aluminum oxide layer 103 has a good passivation effect on the substrate 101. It should be noted that, Figure 1 and Figure 2 In the figure, the entire second surface 121 is taken as a polished surface as an example. In actual applications, only the area of ​​the second surface facing the electrode may be a polished surface, and the area not shielded by the electrode may be a velvet surface or have other surface texture structures to enhance the second surface's absorption effect on incident light and increase the photoelectric conversion efficiency of the photovoltaic cell.

[0050] In other embodiments, the first light may only irradiate the second surface, and / or the second light may only irradiate the first surface.

[0051] In some embodiments, reference Figure 1 or Figure 2 The first surface 111 may be a velvet surface, which can improve the absorption efficiency of the incident light by the first surface 111. In some examples, the velvet surface may be a pyramid velvet surface, which is a common velvet surface, which not only reduces the reflectivity of the first surface, but also forms a light trap, thereby enhancing the absorption effect of the first surface on the incident light and increasing the photoelectric conversion efficiency of the photovoltaic cell.

[0052] It should be noted that, in some embodiments, the battery cell body 100 is a single-sided battery, and the first surface 111 can be regarded as the front side of the battery cell body 100, that is, the first surface 111 can be used as a light-receiving surface for receiving incident light, and the second surface 121 can be used as a backlight surface. In other embodiments, the battery cell body 100 is a double-sided battery, then the first surface 111 and the second surface 121 can both be used as light-receiving surfaces, and can both 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 the incident light is weaker than the degree of receiving the incident light by the light-receiving surface, and therefore it is defined as a backlight surface.

[0053] It is worth noting that for the second photothermal annealing treatment, compared with the improvement of the passivation effect of the substrate 101 after only irradiating the second surface 121 with the second light, the improvement of the passivation effect of the substrate 101 after irradiating both the first surface 111 and the second surface 121 with the second light is better; compared with the improvement of the passivation effect of the substrate 101 after only irradiating the first surface 111 with the second light, the improvement of the passivation effect of the substrate 101 after irradiating the second surface 121 with the second light is better.

[0054] In some embodiments, the step 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 illuminate the first surface 111, the second light source is used to illuminate the second surface 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 located on opposite sides of the battery cell body 100 along the thickness direction, that is, the first light source is located on a side of the first surface 111 away from the second surface 121, and the second light source is located on a side of the second surface 121 away from the first surface 111.

[0055] In some embodiments, the step 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 illuminate the first surface 111, the fourth light source is used to illuminate the second surface 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 located on opposite sides of the battery cell body 100 along the thickness direction, that is, the third light source is located on a side of the first surface 111 away from the second surface 121, and the fourth light source is located on a side of the second surface 121 away from the first surface 111.

[0056] It should be noted that when the first light source and the second light source are provided simultaneously in the first photothermal annealing treatment, the third light source and the fourth light source may be provided simultaneously in the second photothermal annealing treatment, or only one of the third light source and the fourth light source may be provided; when the first light source and one of the second light source are provided in the first photothermal annealing treatment, the third light source and the fourth light source may be provided simultaneously in the second photothermal annealing treatment, or only one of the third light source and the fourth light source may be provided.

[0057] In some examples, various working parameters of the first light source and the second light source, such as light wavelength, light intensity density and irradiation time, etc., can be respectively the same, so that the first photothermal annealing treatment provides the same photothermal annealing environment for the first surface 111 and the second surface 121; 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 first photothermal annealing treatment provides different photothermal annealing environments for the first surface 111 and the second surface 121.

[0058] In some examples, various working parameters of the third light source and the fourth light source, such as light wavelength, light intensity density and irradiation time, etc., can be respectively the same, so that the second photothermal annealing treatment provides the same photothermal annealing environment for the first surface 111 and the second surface 121; 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 second photothermal annealing treatment provides different photothermal annealing environments for the first surface 111 and the second surface 121.

[0059] The design of various working parameters of the first light source, the second light source, the third light source and the fourth light source are described in detail below.

[0060] In some examples, the light intensity density provided by the first light source may be less than the light intensity density provided by the second light source. In other words, the illumination intensity of the first sub-light on the first surface 111 is lower than the illumination intensity of the second sub-light on the second surface 121, which is beneficial for 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.

[0061] It should be noted that, compared with the first surface 111 serving as the light-receiving surface, the second surface 121 serving as the backlight surface generally has a lower light utilization rate. For example, a polysilicon layer may be provided between the substrate 101 and the second aluminum oxide layer 103. The polysilicon layer may reduce the absorption of photon energy by the substrate 101. Therefore, designing the light intensity density provided by the first light source to be smaller than the light intensity density provided by the second light source is beneficial to compensating for the low light utilization rate of the second surface 121 in the first photothermal annealing step, so as to ensure a good passivation effect of the second light source on the second surface 121.

[0062] In some examples, the light intensity density provided by the third light source may be less than the light intensity density provided by the fourth light source. In other words, the illumination intensity of the third sub-light on the first surface 111 is lower than the illumination intensity of the fourth sub-light on the second surface 121, which is beneficial for 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.

[0063] It should be noted that, compared with the first surface 111 serving as the light-receiving surface, the second surface 121 serving as the backlight surface generally has a lower light utilization rate. For example, a polysilicon layer may be provided between the substrate 101 and the second aluminum oxide layer 103. The polysilicon layer may reduce the absorption of photon energy by the substrate 101. Therefore, designing the light intensity density provided by the third light source to be smaller than the light intensity density provided by the fourth light source is beneficial to compensating for the low light utilization rate of the second surface 121 in the second photothermal annealing step, so as to ensure a good passivation effect of the fourth light source on the second surface 121.

[0064] It is worth noting that in actual applications, when the light intensity density provided by the first light source is less than the light intensity density 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 the light intensity density provided by the fourth light source; when the light intensity density provided by the third light source is less than the light intensity density 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 the light intensity density 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 needs.

[0065] In one example, in the first photothermal annealing step, when both the first surface 111 and the second surface 121 are irradiated, the light intensity density provided by the first light source may be 4 kW / m 2 ~8kW / m 2 , for example, it can be 4.5kW / m 2 , 5kW / m 2 、5.5kW / m 2 , 6kW / m 2 、6.5kW / m 2 , 7kW / m 2 or 7.5kW / m 2 The light intensity density provided by the second light source can be 10kW / m 2 ~18kW / m 2 , for example, it can be 10.5kW / m 2 , 11kW / m 2 、11.5kW / m 2 , 12kW / m 2 、12.5kW / m 2 , 13kW / m2 、13.5kW / m 2 , 14kW / m 2 、14.5kW / m 2 , 15kW / m 2 、15.5kW / m 2 、16kW / m 2 、16.5kW / m 2 、17kW / m 2 or 17.5kW / m 2 wait.

[0066] In one example, in the second photothermal annealing step, when both the first surface 111 and the second surface 121 are irradiated, the light intensity density provided by the third light source may be 4 kW / m 2 ~8kW / m 2 , for example, it can be 4.5kW / m 2 , 5kW / m 2 、5.5kW / m 2 , 6kW / m 2 、6.5kW / m 2 , 7kW / m 2 or 7.5kW / m 2 The light intensity density provided by the fourth light source can be 10kW / m 2 ~18kW / m 2 , for example, it can be 10.5kW / m 2 , 11kW / m 2 、11.5kW / m 2 , 12kW / m 2 、12.5kW / m 2 , 13kW / m 2 、13.5kW / m 2 , 14kW / m 2 、14.5kW / m 2 , 15kW / m 2 、15.5kW / m 2 、16kW / m 2 、16.5kW / m 2 、17kW / m 2 or 17.5kW / m 2 wait.

[0067] In some embodiments, in the first photothermal annealing step, only the first surface 111 is irradiated, and in the second photothermal annealing step, at least one of the first surface 111 and the second surface 121 is irradiated, and the light intensity density of the first light can be 10 kW / m 2 ~20kW / m 2The light intensity density of the second light is 6kW / m 2 ~18kW / m 2 It should be noted that the first light only includes the first sub-light for irradiating the first surface 111, the second light includes at least one of the third sub-light for irradiating the first surface 111 and the fourth sub-light for irradiating the second surface 121, and the light intensity density of the third sub-light and the fourth sub-light can both be 6kW / m 2 ~18kW / m 2 .

[0068] In some examples, the light intensity density of the first light can be 10.5 kW / m 2 , 11kW / m 2 、11.5kW / m 2 , 12kW / m 2 、12.5kW / m 2 , 13kW / m 2 、13.5kW / m 2 , 14kW / m 2 、14.5kW / m 2 , 15kW / m 2 、15.5kW / m 2 、16kW / m 2 、16.5kW / m 2 、17kW / m 2 、17.5kW / m 2 、18kW / m 2 、18.5kW / m 2 , 19kW / m 2 or 19.5kW / m 2 wait.

[0069] In some examples, the light intensity density of the second light can be 6.5 kW / m 2 , 7kW / m 2 、10.5kW / m 2 、7.5kW / m 2 , 8kW / m 2 、8.5kW / m 2 , 9kW / m 2 , 9.5kW / m 2 , 10kW / m 2 、10.5kW / m 2 , 11kW / m 2 、11.5kW / m 2 , 12kW / m 2 、12.5kW / m 2 , 13kW / m 2 、13.5kW / m2 , 14kW / m 2 、14.5kW / m 2 , 15kW / m 2 、15.5kW / m 2 、16kW / m 2 、16.5kW / m 2 、17kW / m 2 or 17.5kW / m 2 wait.

[0070] In some examples, the processing time of the first photothermal annealing treatment can be 30s to 50s, for example, 31s, 32s, 33s, 34s, 35s, 36s, 37s, 38s, 39s, 40s, 41s, 42s, 43s, 44s, 45s, 46s, 47s, 48s or 49s, etc.; the processing time of the second photothermal annealing treatment is 2s to 15s, for example, 3s, 4s, 5s, 6s, 7s, 8s, 9s, 10s, 11s, 12s, 13s or 14s, etc.

[0071] In some examples, when only the first surface 111 is irradiated in the first photothermal annealing step and only the second surface 121 is irradiated in the second photothermal annealing step, the treatment time of the first photothermal annealing can be 30s~50s, and the treatment time of the second photothermal annealing is 8s~15s.

[0072] In other examples, when only the first surface 111 is irradiated in the first photothermal annealing step and only the first surface 111 is irradiated in the second photothermal annealing step, the treatment time of the first photothermal annealing can be 30s~50s, and the treatment time of the second photothermal annealing is 3s~7s.

[0073] In some other examples, when only the first surface 111 is irradiated in the first photothermal annealing treatment step, and both the first surface 111 and the second surface 121 are irradiated in the second photothermal annealing treatment step, the treatment time of the first photothermal annealing treatment can be 30s~50s, and the treatment time of the second photothermal annealing treatment is 6s~10s.

[0074] In the various embodiments described above, the heating temperature of the first photothermal annealing treatment may be greater than the heating temperature of the second photothermal annealing treatment. It is worth noting 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 play a passivation effect to the substrate 101, so as to increase the probability that the surface defects of the substrate 101 are passivated by ions. Based on this, the heating temperature of the first photothermal annealing treatment is designed to be greater than the heating temperature of the second photothermal annealing treatment, which is conducive to controlling the heating temperature of the second photothermal annealing treatment to be lower while making the passivation effect of the substrate 101 better with the help of the first photoannealing treatment, so as to shorten the cooling time, so as to facilitate the subsequent timely IV (current-voltage) test of the prepared photovoltaic cell, thereby shortening the length of the equipment required for preparing photovoltaic cells and improving the life of the transmission belt.

[0075] In one example, the heating temperature of the first photothermal annealing treatment can be 240℃~300℃, for example, it can be 245℃, 250℃, 255℃, 260℃, 265℃, 270℃, 275℃, 280℃, 285℃, 290℃ or 295℃, etc.; the heating temperature of the second photothermal annealing treatment can be 50℃~140℃, for example, it can be 55℃, 60℃, 65℃, 70℃, 75℃, 80℃, 85℃, 90℃, 95℃, 100℃, 105℃, 110℃, 115℃, 120℃, 125℃, 130℃ or 135℃, etc.

[0076] In the above various embodiments, the step of performing the first photothermal annealing treatment may include: controlling the light intensity density of the first light to gradually change within the treatment time of the first photothermal annealing treatment, and / or controlling the heating temperature of the first photothermal annealing treatment to gradually change within the treatment time of the first photothermal annealing treatment.

[0077] It should be noted that controlling the light intensity density of the first light to gradually change during the treatment time of the first photothermal annealing treatment may 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 during the treatment time of the first photothermal annealing treatment may 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 beneficial to make the temperature of the surface of the photovoltaic cell controllable, and it is not easy to cause the phenomenon that pollutants on the transmission belt adhere to the surface of the photovoltaic cell.

[0078] Among them, controlling the light intensity density of the first light to gradually decrease or first gradually increase and then gradually decrease, or controlling the heating temperature of the first photothermal annealing treatment to gradually decrease or first gradually increase and then gradually decrease, are all beneficial to shortening the cooling time, so as to facilitate the subsequent timely IV (current-voltage) test of the prepared photovoltaic cells, thereby facilitating the shortening of the equipment length required for preparing photovoltaic cells and improving the life of the transmission belt.

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

[0080] It should be noted that controlling the light intensity density of the second light to gradually change during the treatment time 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 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 during the treatment time 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 beneficial to make the temperature of the surface of the photovoltaic cell controllable, and it is not easy to cause 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 second light to gradually decrease or first gradually increase and then gradually decrease, or controlling the heating temperature of the second photothermal annealing treatment to gradually decrease or first gradually increase and then gradually decrease, are all beneficial to shortening the cooling time, so as to facilitate the subsequent timely IV (current-voltage) test of the prepared photovoltaic cells, thereby facilitating the shortening of the equipment length required for preparing photovoltaic cells and improving the life of the transmission belt.

[0082] In some embodiments, a method for controlling the gradual change of the light intensity density of the first light within the processing time of the first photothermal annealing treatment includes: designing at least one of the first light source or the second light source to include multiple lamp groups connected in series, and taking power to control the gradual change of the light intensity of the multiple lamp groups; a method for controlling the gradual change of the light intensity density of the second light within the processing time of the second photothermal annealing treatment includes: designing at least one of the third light source or the fourth light source to include multiple lamp groups connected in series, and taking power to control the gradual change of the light intensity of the multiple lamp groups.

[0083] In some embodiments, the laser enhanced contact processing may be a laser assisted sintering technology, also known as laser enhanced contact optimization, which is used to improve the contact between the electrode and the silicon wafer in the photovoltaic cell. In the laser enhanced contact processing, the laser is used for non-destructive carrier injection. After the laser enhanced contact processing, the contact resistance between the electrode and the silicon wafer in the photovoltaic cell is significantly reduced, which is beneficial to improve the open circuit voltage and short circuit current of the photovoltaic cell.

[0084] 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, and the photon energy of the first light is larger, which is conducive to deep activation of the first aluminum oxide layer 102 and / or the second aluminum oxide layer 103, for example, increasing the content of hydrogen ions in the first aluminum oxide layer 102 and / or the second aluminum oxide layer 103, so as to enhance the passivation effect of the first aluminum oxide layer 102 and / or the second aluminum oxide layer 103 on the surface of the substrate 101; on the other hand, compared with the second 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 enough to break the silicon-hydrogen bond on the surface of the substrate 101. The second light is incident on the shallow surface of the photovoltaic cell, and the first aluminum oxide layer 102 and / or the second aluminum oxide layer 103 are activated for the second time, which is beneficial to improve the contact performance between the electrode and the substrate 101, such as reducing the metal recombination probability between the electrode and the substrate 101; on the other hand, the first photoannealing treatment and the second photoannealing treatment are carried out before and after the laser enhanced contact treatment, which is beneficial to improve the life of minority carriers. In this way, the combined effect of multiple aspects is beneficial to improve the photoelectric conversion efficiency of the photovoltaic cell finally prepared.

[0085] Another embodiment of the present disclosure also provides a photovoltaic cell, which is prepared by the preparation method provided in the above embodiment. The photovoltaic cell provided in another embodiment of the present disclosure will be described in detail below in conjunction with the accompanying drawings. It should be noted that the parts that are the same or corresponding to the above embodiment will not be repeated here.

[0086] refer to Figure 1 or Figure 2 , the photovoltaic cell includes: a photovoltaic cell formed according to the preparation method provided in the above embodiment.

[0087] It is worth noting 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. The photovoltaic cell is formed according to the preparation method provided in the above embodiment, and the first photoannealing treatment and the second photoannealing treatment are performed before and after the laser enhanced contact treatment, which is conducive to improving the photoelectric conversion efficiency of the formed photovoltaic cell.

[0088] Those skilled in the art can understand that the above-mentioned embodiments are specific examples for implementing the present disclosure, and in practical applications, various changes can be made to them in form and detail 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, so the protection scope of the embodiments of the present disclosure shall be based on the scope defined in 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; 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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