Back contact solar cell and production method, and back contact battery assembly

Abstract

A back-contacting solar cell and a producing method, and a back-contacting cell assembly, which relates to the technical field of photovoltaics. The back-contacting solar cell includes: a silicon substrate (1), wherein a shadow face of the silicon substrate (1) is delimited into a first region and a second region (2), and the second region (2) is doped to form a second-charge-carrier collecting end; a metal-chalcogen-compound layer (4), wherein the metal-chalcogen-compound layer (4) is deposited within at least the first region of the silicon substrate (1), and a region of the metal-chalcogen-compound layer (4) that corresponds to the first region forms a first-charge-carrier collecting end; a first electrode (5), wherein the first electrode (5) is correspondingly provided on the first-charge-carrier collecting end; and a second electrode (6), wherein the second electrode (6) is correspondingly provided within a region that corresponds to the second region (2). The collection and transferring of the first charge carrier are realized by using the first-charge-carrier collecting end. The metal-chalcogen-compound layer (4) has a good adjustability in the structure and the performance, a good thermal stability, and a wide window of process selection, and can realize a lower transverse-conduction capacity and a higher longitudinal-conduction capacity.

Description

Back contact solar cells and their manufacturing methods, back contact solar cell modules

[0001] This application claims priority to the following Chinese patent applications filed on June 15, 2020: Application No. 202010544465.9, entitled "Back Contact Solar Cell and Manufacturing Method, Back Contact Battery Module"; Application No. 202021106709.7, entitled "IBC Battery and IBC Module"; Application No. 202021108338.6, entitled "Full Back Electrode Solar Cell and Full Back Electrode Battery Module"; and Application No. 202021101871.X, entitled "Solar Cell and Photovoltaic Module", the entire contents of which are incorporated herein by reference. Technical Field

[0002] This invention relates to the field of photovoltaic technology, and in particular to a back-contact solar cell and its manufacturing method, and a back-contact cell module. Background Technology

[0003] Back-contact solar cells have a wide range of applications because the light-facing side is completely unblocked by electrodes, which can achieve high photoelectric conversion efficiency.

[0004] Currently, back-contact solar cells typically require the fabrication of precisely aligned and electrically isolated regions of different conductivity types on the back surface of a silicon substrate.

[0005] However, the process of creating regions of different conductivity types that are accurately aligned and electrically isolated from each other results in poor process stability.

[0006] Summary of the Invention

[0007] This invention provides a back-contact solar cell and its manufacturing method, as well as a back-contact solar cell assembly, aiming to solve the problem of poor process stability.

[0008] According to a first aspect of the present invention, a back-contact solar cell is provided, comprising: a silicon substrate, the back surface of the silicon substrate being divided into a first region and a second region; a metal oxidant compound layer, at least deposited in the first region of the silicon substrate; the metal oxidant compound layer forming a first carrier collection terminal in a region corresponding to the first region; a first electrode correspondingly disposed on the first carrier collection terminal; and a second electrode correspondingly disposed in a region corresponding to the second region.

[0009] At the interface near the first region, the conduction band energy level of the metal oxidase layer is close to the conduction energy level of the first charge carrier in the first region. This allows it to absorb the first charge carrier and repel the second charge carrier. Thus, the region corresponding to the metal oxidase layer and the first region forms a first charge carrier collection terminal, enabling the collection and transport of the first charge carrier. The metal oxidase layer exhibits strong structural and performance tunability, good thermal stability, and a wide process selection window. Furthermore, it can achieve low lateral conductivity and strong longitudinal conductivity.

[0010] Optionally, the silicon substrate in the second region is doped to form a second carrier collection terminal; the metal oxidant compound layer is deposited on the back surface of the entire silicon substrate; the region corresponding to the metal oxidant compound layer and the second region forms a second carrier transport region; and the second electrode is correspondingly disposed on the second carrier transport region.

[0011] In this embodiment of the invention, the second carrier collection terminal is formed by doping a second region on the back surface of the silicon substrate. This second region absorbs second carriers and repels first carriers, thus exhibiting selectivity. Consequently, the second carrier density is higher and the first carrier density is lower at the second carrier collection terminal. Meanwhile, the continuous metal oxidase layer near the interface of the first region has a carrier conduction energy level close to that of the first carrier in the first region. This allows it to absorb first carriers and repels second carriers. Therefore, the region corresponding to the metal oxidase layer and the first region forms the first carrier collection terminal, enabling the collection and transport of first carriers. Because the second carrier density is high and the first carrier density is low at the second carrier collection end, the carrier conduction energy level of the metal oxidant (MEA) layer is close to the conduction energy level of the second carrier in the second region. Therefore, the second carriers at the second carrier collection end can directly enter the region corresponding to the second region of the MEA layer. Consequently, the region corresponding to the second region of the MEA layer serves as the second carrier transport region, realizing the collection and transport of the second carriers. In other words, in the MEA layer, the region corresponding to the first region realizes the collection and transport of the first carriers, while the region corresponding to the second region realizes the collection and transport of the second carriers. That is, different regions of the MEA layer realize the transport of the second carriers and the collection of the first carriers, respectively. At the same time, the MEA layer has low lateral transport capability. After different types of carriers are collected, they are all transported longitudinally into the corresponding electrodes, without interconnection due to lateral transport, which would lead to leakage or short circuits. Therefore, no additional alignment and electrical isolation are required, the process is simple, recombination is reduced, and the photoelectric conversion efficiency is improved. Meanwhile, the second carrier collection terminal, the first carrier collection terminal, and the metal oxo compound layer will not form a reverse pn junction due to mutual contact.

[0012] Optionally, the silicon substrate in the second region is doped to form a second carrier collection terminal; the metal oxo compound layer is deposited only on the first region; and the second electrode is correspondingly disposed on the second carrier collection terminal.

[0013] or,

[0014] The metal oxidant compound layer is deposited on the back surface of the entire silicon substrate; at least a portion of the metal oxidant compound layer corresponding to the second region has an opening that electrically divides the metal oxidant compound layer; a second carrier selection layer is formed on the portion of the metal oxidant compound layer corresponding to the second region, and the second carrier selection layer fills the opening; the second electrode is correspondingly disposed on the second carrier selection layer.

[0015] In this embodiment of the invention, the second carrier collection terminal is formed by doping a second region on the back surface of the silicon substrate. This allows it to absorb second carriers and repel first carriers, thus achieving selectivity for the second carriers. Consequently, the second carrier density is higher and the first carrier density is lower at the second carrier collection terminal. The metal oxometalate layer, serving as the first carrier collection terminal, is deposited only on a first region on the back surface of the silicon substrate. Its carrier conduction energy level is close to that of the first carriers in the first region, allowing it to absorb first carriers and repel second carriers. This first carrier collection terminal thus enables the collection and transport of the first carriers. The first electrode is disposed on the first carrier collection terminal, and the second electrode is disposed on the second carrier collection terminal. That is, the second region of the back surface of the doped silicon substrate realizes the collection and transport of the second carriers, while only the metal oxo compound layer deposited on the first region of the back surface of the silicon substrate realizes the collection and transport of the first carriers. Different materials located at different positions realize the collection and transport of different carriers respectively. No additional alignment and electrical isolation are required, the process is simple, the area of ​​the non-collection region is reduced, and the photoelectric conversion efficiency is improved. At the same time, the carrier conduction energy level of the collection or conduction material in each carrier collection region is close to the transport energy level of the corresponding carrier in the silicon material, and the transport interface has no or low potential barrier, reducing the longitudinal contact resistance. Alternatively, based on the absorption of second charge carriers and repulsion of first charge carriers at the second charge carrier collection end, thus achieving the selective effect of second charge carriers, the continuous metal oxidant layer near the interface of the first region has a charge carrier conduction energy level close to that of the first charge carrier in the first region. This can absorb the first charge carriers and repel the second charge carriers, thereby forming the first charge carrier collection end in the portion of the metal oxidant layer corresponding to the first region. The collection and transport of the first charge carriers are achieved through the first charge carrier collection end. At least the portion of the continuous metal oxidant layer corresponding to the second region has an opening that electrically divides the metal oxidant layer. The opening is filled with a second charge carrier selective layer, and the second electrode is disposed on the second charge carrier selective layer. This means that the second charge carriers are transported specifically through the second charge carrier selective layer, while the first charge carriers are mainly transported through the unopened portion of the metal oxidant layer. This achieves the transport of different charge carriers by different substances, without the need for additional alignment and electrical isolation. The process is simple, the area of ​​the uncollected region is reduced, and the photoelectric conversion efficiency is improved. Meanwhile, the first and second charge carriers are transported through different materials, and the second charge carrier selection layer facilitates the transport of the second charge carriers, which can reduce the longitudinal contact resistance. Furthermore, the second charge carrier collection terminal, the first charge carrier collection terminal, and the metal oxo compound layer will not form a reverse pn junction due to mutual contact.

[0016] Optionally, the silicon substrate in the second region is doped to form a second carrier collection terminal; the metal oxidant layer is deposited on the back surface of the entire silicon substrate; the metal oxidant layer has a blocking structure that electrically divides the metal oxidant layer into a second carrier transport region and a first carrier collection terminal; wherein the second carrier transport region corresponds to the second region; and the second electrode is correspondingly disposed on the second carrier transport region.

[0017] In this embodiment of the invention, the second carrier collecting end is formed by doping a second region on the back surface of the silicon substrate. This allows it to absorb second carriers and repel first carriers, thus achieving selectivity for the second carriers. Consequently, the second carrier density is higher and the first carrier density is lower at the second carrier collecting end. The blocking structure electrically divides the metal-oxide-semiconductor layer into a second carrier transport region and a first carrier collecting end. At the interface near the first region, the carrier conduction energy level at the first carrier collecting end is close to the conduction energy level of the first carriers in the first region, allowing it to absorb first carriers and repel second carriers. Because the second carrier density is higher and the first carrier density is lower at the second carrier collecting end, and the carrier conduction energy level in the second carrier transport region is close to the conduction energy level of the corresponding second carriers in the second region, the second carriers at the second carrier collecting end can directly enter the second carrier transport region, achieving the collection and transport of second carriers. Simultaneously, by dividing the second carrier transport region and the first carrier collection terminal through a blocking structure, the lateral transport capability of the entire metal oxometalate layer is very low. This improves the longitudinal conductivity of the metal oxometalate layer and avoids lateral leakage, thereby significantly reducing the longitudinal series resistance. Furthermore, by dividing the second carrier transport region and the first carrier collection terminal through the blocking structure, different types of carriers are collected and transported longitudinally to their respective electrodes, preventing them from interconnecting due to lateral transport and causing leakage or short circuits. Therefore, precise doping alignment is not required, simplifying the process, reducing recombination, and improving photoelectric conversion efficiency. Additionally, the second carrier collection terminal, the first carrier collection terminal, and the metal oxometalate layer will not form a reverse pn junction due to mutual contact.

[0018] Optionally, the back-contact solar cell further includes: a second carrier selective collection layer; the second carrier selective collection layer is deposited on the second region of the silicon substrate; the metal oxidant compound layer is deposited on the first region and the back surface of the second carrier selective collection layer; a portion of the metal oxidant compound layer corresponding to the second carrier selective collection layer forms a second carrier transport region; and a second electrode is disposed on the second carrier transport region.

[0019] In this embodiment of the invention, the second carrier selective collection layer is deposited on a second region of the backlight surface of the silicon substrate, requiring no high-temperature diffusion and employing a low processing temperature. The carrier conduction energy level of the second carrier selective collection layer is close to the second carrier conduction energy level of the silicon substrate, allowing it to absorb second carriers and repel first carriers, thus achieving selectivity for the second carriers. At the interface of the metal oxometalate layer outside the second carrier selective collection layer, the carrier conduction energy level is close to the conduction energy level of the first carriers in the first region of the backlight surface of the silicon substrate, allowing it to absorb first carriers and repel second carriers. Therefore, the region outside the second carrier transport region in the metal oxometalate layer forms a first carrier collection terminal, enabling the collection and transport of first carriers. In other words, the metal oxometalate (MOF) layer region corresponding to the second carrier selective collection layer enables the transport of the second carriers, while the remaining MOF layer regions enable the collection and transport of the first carriers. That is, different regions of the MOF layer respectively achieve the transport of the second carriers and the collection of the first carriers. Simultaneously, the interface between the second carrier transport region and the first carrier collection terminal in the MOF layer contains high-resistivity defects, which provide insulation, preventing leakage or short circuits. Therefore, no additional alignment or electrical isolation is required, simplifying the process, reducing recombination, and improving photoelectric conversion efficiency. The second carrier selective collection layer employs a deposited selective contact structure, and the MOF layer also employs a deposited selective contact structure, offering the advantage of low bulk recombination and not being limited by the Auger recombination limit. Furthermore, the second carrier selective collection layer and the first carrier collection terminal do not form a reverse pn junction due to mutual contact.

[0020] According to a second aspect of the present invention, a method for manufacturing a back-contact solar cell is provided, comprising:

[0021] A silicon substrate is provided; the backlight surface of the silicon substrate is divided into a first region and a second region;

[0022] A metal oxidant compound layer is deposited in at least the first region of the silicon substrate; the metal oxidant compound layer forms a first carrier collection terminal in the region corresponding to the first region;

[0023] A first electrode is correspondingly disposed on the first carrier collection terminal;

[0024] A second electrode is disposed in the area corresponding to the second region.

[0025] According to a third aspect of the present invention, a back-contact battery assembly is provided, comprising: any of the aforementioned back-contact solar cells.

[0026] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, and in order to make the above and other objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention are described below. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0028] Figures 1-23 show schematic diagrams of the first to twenty-third types of back-contact solar cells in the embodiments of the present invention.

[0029] Explanation of the attached drawing numbers:

[0030] 1-Silicon substrate, 2-Second region, 3-Tunneling isolation layer, 4-Metal oxometalate layer, 22-Second carrier selection layer, 23-Second carrier selection and collection layer, 5-First electrode, 6-Second electrode, 52-First transparent conductive film, 53-First work function adjustment layer, 63-Second transparent conductive film, 62-Second work function adjustment layer, 64-Third work function adjustment layer, 65-Third transparent conductive film, 66-Fourth work function adjustment layer, 67-Fourth transparent conductive film, 68-Fifth work function adjustment layer, 69-Fifth transparent conductive film, 7-Front-side anti-reflection film layer, 8-Back-side passivation film or back-side anti-reflection film, 9-Blocking structure. Specific Implementation

[0031] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0032] In an embodiment of the present invention, referring to FIG1, FIG1 shows a schematic diagram of the structure of a first type of back-contact solar cell according to an embodiment of the present invention. The back-contact solar cell includes: a silicon substrate 1, the back surface of the silicon substrate 1 being divided into a first region and a second region 2. In FIG1, the region on the back surface of the silicon substrate 1 other than the second region 2 is the first region.

[0033] The metal oxide layer 4 is deposited at least in the first region of the silicon substrate 1. It should be noted that whether the metal oxide layer 4 is deposited in the second region 2 of the silicon substrate 1 is not specifically limited. For example, in the back contact solar cell shown in Figure 1, the second region 2 of the silicon substrate 1 does not have the metal oxide layer 4 deposited.

[0034] The region corresponding to the first region of the backlight surface of the metal oxo compound layer 4 and the silicon substrate 1 forms a first carrier collection terminal, which can realize the collection and transmission of the first carriers.

[0035] It is understood that only two charge carriers exist in a back-contact solar cell. Therefore, the first charge carrier is selected from either the majority carrier or the minority carrier, and the second charge carrier is the other. That is, when the first charge carrier is the majority carrier, the second charge carrier must be the minority carrier; when the second charge carrier is the majority carrier, the first charge carrier must be the minority carrier. It should be noted that in this invention, whether the majority carrier or the minority carrier is an electron or a hole depends primarily on the doping type of the silicon substrate 1. If the silicon substrate 1 is doped n-type, then in the back-contact solar cell of this invention, the majority carrier refers to electrons, and the minority carrier refers to holes. If the silicon substrate 1 is doped p-type, then in the back-contact solar cell of this invention, the majority carrier refers to holes, and the minority carrier refers to electrons.

[0036] In the metal oxometalate layer 4, a first electrode 5 is disposed at the first carrier collection end, and the first electrode 5 is used to conduct the first carriers. A second electrode 6 is disposed in the corresponding region of the second region 2, and the second electrode 6 is used to conduct the second carriers. It should be noted that an electrical insulation gap must be maintained between the first electrode 5 and the second electrode 6, and the electrical insulation gap must be not less than the breakdown distance under normal operating voltage. The first electrode 5 and the second electrode 6 can be fabricated using processes such as printing or deposition. The second electrode 6 and the first electrode 5 can be metal electrodes.

[0037] At the interface near the first region, the conduction band energy level of the metal oxidant layer 4 is close to the conduction energy level of the first charge carrier in the first region. This allows it to absorb the first charge carrier and repel the second charge carrier. Thus, the region corresponding to the metal oxidant layer 4 and the first region forms a first charge carrier collection terminal, enabling the collection and transport of the first charge carrier. The metal oxidant layer 4 exhibits strong structural and performance tunability, good thermal stability, and a wide process selection window. Furthermore, it can achieve both low lateral conductivity and strong longitudinal conductivity.

[0038] Optionally, referring to Figure 2, which shows a schematic diagram of the structure of a second type of back-contact solar cell in an embodiment of the present invention, a metal oxide compound layer 4 is deposited on the back surface of the entire silicon substrate 1. Compared with depositing other material layers on the back surface of the entire silicon substrate 1, this method offers greater structural and performance adjustability, achieves lower lateral conductivity and stronger longitudinal conductivity, and exhibits better thermal stability and a wider process selection window.

[0039] In Figure 2, the region corresponding to the second region of the backlight surface of the metal oxidant layer 4 and the silicon substrate 1 forms a second carrier transport region, which enables the transport of second carriers. A second electrode 6 is disposed in the second carrier transport region of the metal oxidant layer 4, and the second electrode 6 is used to conduct the second carriers.

[0040] Optionally, the second region 2 described above is doped to form a second carrier collection terminal. The second carrier collection terminal can collect and transport second carriers. It should be noted that the doping type of the second region 2 and the second region in the silicon substrate 1 may be the same or different; when the doping type is the same, the doped elements may be the same or different, and this embodiment of the present invention does not specifically limit this.

[0041] Optionally, the area of ​​the projection of the second carrier collection terminal onto the back surface of the silicon substrate 1 accounts for 5% to 45% of the total area of ​​the back surface of the silicon substrate. At this area ratio, the collection and transport of the second carriers are effective, while not affecting the collection and transport of the first carriers.

[0042] Optionally, the top view of the second carrier collection terminal can be a dotted or line pattern. Dotted patterns can be, for example, circular or elliptical shapes. Line patterns can be, for example, rectangular or polygonal shapes. Using a dotted or line pattern for the top view of the second carrier collection terminal simplifies the doping process for the second region.

[0043] Optionally, the doping concentration at the second carrier collector is greater than or equal to 10. 15 cm -3 Furthermore, the doping concentration is greater than that of the silicon substrate 1 in the first region, which improves the collection and transport of the second charge carriers.

[0044] Referring to Figure 2, the following explanation uses an n-type silicon substrate 1, with electrons as the second charge carrier and holes as the first charge carrier. The second charge carrier collecting end is a doped structure, which causes the energy band of the n-type silicon substrate to bend downwards in the second region 2, attracting electrons and repelling holes, thus achieving electron selective collection. The region in the metal oxidant layer 4 corresponding to the first region forms the first charge carrier collecting end, which is also the hole collecting end. The metal oxidant compound (i.e., the first charge carrier collecting end) in the first region acts as a hole-selective contact material. The conduction band energy level of this material is close to the valence band energy level of the n-type silicon substrate, and it can possess a negative interface charge or negative fixed defects, causing the energy band at the interface to bend upwards, forming a p-type interface layer, which attracts holes and repels electrons. At the first charge carrier collecting end, the highly selective material causes strong interface energy band bending. Simultaneously, the conduction band bottom energy level of the first charge carrier collecting end is low, allowing holes to enter the hole-selective material through tunneling recombination, achieving hole collection and transport. In the second carrier transport region, due to the high electron density and low hole density, the conduction band bottom energy level in this region is low and close to the conduction band bottom energy level of the second carrier collection end. Therefore, electrons can directly enter the second carrier transport region in the metal oxo compound layer corresponding to the second carrier collection end, thereby realizing electron transport.

[0045] It should be noted that the conduction band energy level and valence band energy level in this invention generally refer to the energy level of the material itself, that is, the energy level when the material exists alone, and not the actual energy level in the battery structure.

[0046] In Figure 2, the metal oxo compound layer 4 can simultaneously collect holes and transport electrons. At the same time, the material can be made to have low lateral conductivity by adjusting its crystallinity, crystal phase and doping elements. Holes in the first carrier collection terminal and electrons in the second carrier transport region are longitudinally transported into the corresponding electrodes after different types of carriers are collected. They will not be interconnected due to lateral transport, which would cause leakage or short circuit. Therefore, different types of carrier collection terminals do not need to be electrically isolated and will not generate reverse pn junctions due to mutual contact.

[0047] In Figure 2, the second carrier collection end adopts a locally doped selective contact structure, and the metal oxide layer 4 adopts a deposited selective contact structure. Compared with the traditional fully diffused back contact structure, it has the advantages of low bulk recombination in the minority carrier collection region, and fewer diffusion steps, making the process relatively simple. Compared with the structure using amorphous silicon as the back contact, the metal oxide layer 4 has stronger selectivity, higher thermal stability, and lower equipment requirements for the material deposition process, resulting in higher safety. The metal oxide layer 4 can fully cover the back of the battery, further simplifying the process flow.

[0048] The first carrier collection end is formed by using the region corresponding to the first region in the metal oxo compound layer 4. Compared with amorphous silicon materials, it has stronger selectivity and longitudinal transport capability, and the first carrier collection and longitudinal transport capabilities are stronger. At the same time, in the second carrier collection end, in conjunction with the localized doping structure, the second carrier transport is carried out through the band edge of the oxo compound material, without involving the cross-level tunneling mechanism. The second carrier transport has low resistance and can achieve lower contact resistance.

[0049] Optionally, the metal oxo compound layer 4 can be a single layer or multiple layers. Referring to Figures 1 and 2, the thickness d1 of the metal oxo compound layer 4 can be 1-600 nm, more preferably 2-100 nm. This thickness range is beneficial for the transport and collection of the second charge carrier and the first charge carrier.

[0050] In other cases, such as when silicon substrate 1 is a p-type silicon substrate and the second charge carrier is a hole, the above understanding can be used as a reference.

[0051] Optionally, when the silicon substrate is an n-type silicon substrate and the second charge carrier is a majority carrier, or when the silicon substrate is a p-type silicon substrate and the second charge carrier is a minority carrier, the material of the metal oxidant layer 4 is selected from at least one of the first materials. The first material is an n-type metal oxide with a work function greater than or equal to 5 eV, or a p-type metal oxide with a work function less than or equal to 6 eV. In both cases, the second charge carrier transport region in the metal oxidant layer 4 of this material facilitates the transport of the second charge carrier, and the first charge carrier collection end in the metal oxidant layer 4 of this material facilitates the transport and collection of the first charge carrier.

[0052] Specifically, when the silicon substrate is an n-type silicon substrate and the second charge carrier is an electron, or when the silicon substrate is a p-type silicon substrate and the second charge carrier is an electron, the material of the metal oxo compound layer 4 is selected from at least one of the first materials mentioned above.

[0053] Optionally, the first material is selected from at least one of: molybdenum oxide, tungsten oxide, vanadium oxide, niobium oxide, nickel oxide, mercury-doped niobium oxide (such as Hg2Nb2O7), and mercury-doped tantalum oxide (such as Hg2Ta2O7). When the silicon substrate is an n-type silicon substrate and the second charge carrier is an electron, or when the silicon substrate is a p-type silicon substrate and the second charge carrier is an electron, the first charge carrier collection end in the metal oxidant layer 4 of the aforementioned material facilitates the transport and collection of the first charge carrier, and the second charge carrier transport region in the metal oxidant layer 4 of the aforementioned material facilitates the transport of the second charge carrier.

[0054] Optionally, when the silicon substrate is a p-type silicon substrate and the second charge carrier is a majority carrier, or when the silicon substrate is an n-type silicon substrate and the second charge carrier is a minority carrier, the material of the metal oxidant layer is selected from at least one of the second materials; the second material is a metal oxidant with a work function greater than or equal to 3 eV. The second charge carrier transport region in the metal oxidant layer 4 of this material facilitates the transport of the second charge carrier, and the first charge carrier collection end in the metal oxidant layer 4 of this material facilitates the transport and collection of the first charge carrier.

[0055] Specifically, when the silicon substrate is a p-type silicon substrate and the second charge carrier is a hole, or when the silicon substrate is an n-type silicon substrate and the second charge carrier is a hole, the material of the metal oxo compound layer 4 is selected from at least one of the above-mentioned second materials.

[0056] Optionally, the second material mentioned above is selected from: zinc oxide, tin oxide, titanium oxide, copper oxide, thallium oxide, cadmium sulfide, molybdenum sulfide, zinc sulfide, molybdenum selenide, copper selenide, niobium-doped copper oxide (such as CuNb3O8), and cadmium-germanium oxide (such as Ce). 0.8 Gd 0.2 At least one of O2), zinc iridium oxide (such as ZnIr2O4), and calcium cobalt oxide (such as Ca3Co4O9). When the silicon substrate is a p-type silicon substrate and the second charge carrier is a hole, or when the silicon substrate is an n-type silicon substrate and the second charge carrier is a hole, the second charge carrier transport region in the metal oxidant layer 4 of this material facilitates the transport of the second charge carrier, and the first charge carrier collection end in the metal oxidant layer 4 of this material facilitates the transport and collection of the first charge carrier.

[0057] Optionally, the aforementioned metal oxidase compound contains a dopant element selected from at least one of the following: halogen elements, transition metal elements, alkali metal elements, rare earth elements, group III elements, group IV elements, and group V elements. The second carrier transport region in the metal oxidase compound layer 4 of the aforementioned material facilitates the transport of second carriers, and the first carrier collection end in the metal oxidase compound layer 4 of the material facilitates the transport and collection of first carriers.

[0058] Optionally, the lateral conductivity of the metal oxo compound layer 4 is less than or equal to 1.0 × 10⁻⁶. -3 S / cm, transverse resistance greater than or equal to 1.0 × 10 3 With a conductivity of Ω / cm, it effectively blocks lateral current. Lateral conductivity can be reduced by adjusting the material structure, such as crystallinity, crystal phase, or doping processes.

[0059] Optionally, in Figure 2, when the silicon substrate is a p-type silicon substrate and the second charge carrier is a majority carrier, or when the silicon substrate is an n-type silicon substrate and the second charge carrier is a minority carrier, the region corresponding to the first region of the metal oxidant layer 4 forms a first charge carrier collecting end for collecting and transporting first charge carrier electrons, and the region corresponding to the second region of the metal oxidant layer 4 forms a second charge carrier transport region for transporting second charge carrier holes. The fixed positive charge density at the interface or inside the metal oxidant layer 4 is greater than or equal to 10. 11 cm -2 And / or, the acceptor defect density at the interface or within the metal oxo compound layer 4 is greater than or equal to 10. 11 cm -2 And / or, the site charge density at the interface or within the metal oxometalate layer 4 is greater than or equal to 10. 11 cm -2 The second carrier transport region in the metal oxidant layer 4 of this material facilitates the transport of the second carrier, while the first carrier collection end in the metal oxidant layer 4 of this material facilitates the transport and collection of the first carrier.

[0060] Optionally, in Figure 2, when the silicon substrate is an n-type silicon substrate and the second charge carrier is a majority carrier, or when the silicon substrate is a p-type silicon substrate and the second charge carrier is a minority carrier, the region corresponding to the first region of the metal oxidase layer 4 forms a first charge carrier collecting end for collecting and transporting the first charge carrier holes, and the region corresponding to the second region of the metal oxidase layer 4 forms a second charge carrier transport region for transporting the second charge carrier electrons. The fixed negative charge density at the interface or inside the metal oxidase layer 4 is greater than or equal to 10. 12 cm -2 And / or, the donor defect density at the interface or within the metal oxo compound layer 4 is greater than or equal to 10. 12 cm -2 And / or, the site charge density at the interface or within the metal oxometalate layer 4 is greater than or equal to 10. 12 cm -2 The second carrier transport region in the metal oxidant layer 4 of this material facilitates the transport of the second carrier, while the first carrier collection end in the metal oxidant layer 4 of this material facilitates the transport and collection of the first carrier.

[0061] Optionally, the metal oxo compound layer 4 has an average transmittance of 70% or more in the visible light band. Consequently, the metal oxo compound layer 4 blocks less visible light, which is beneficial to improving photoelectric conversion efficiency.

[0062] Optionally, the back surface of the silicon substrate 1 is a planar structure or a light-trapping structure, and the light-facing surface of the metal oxide compound layer 4 is adapted to the back surface of the silicon substrate 1. And / or, the light-facing surface of the silicon substrate 1 is a planar structure or a light-trapping structure. For the light-trapping structure, the optical path can be increased, improving the photoelectric conversion efficiency. The light-trapping structure can be a textured surface, an inverted pyramid, a nanostructure, etc.

[0063] Optionally, the light-facing surface of the silicon substrate may also be provided with at least one of the following: a passivation layer, a front field-effect layer, a front anti-reflection film layer, a scattering structure layer, and a light-concentrating structure layer. And / or, in the back-facing surface of the metal oxometalate layer, a back passivation film is provided in the area other than the second electrode and the first electrode to achieve passivation, optical improvement, etc.

[0064] For example, referring to FIG3, FIG3 shows a schematic diagram of the structure of a third type of back-contact solar cell in an embodiment of the present invention. In FIG3, 7 can be the front anti-reflection thin film layer, and 8 can be the back passivation film.

[0065] Optionally, referring to Figure 4, which shows a schematic diagram of the fourth type of back-contact solar cell in this embodiment of the invention, a second carrier selection layer 22 is also deposited on the back surface of the second region 2. This second carrier selection layer 22 can further enhance the transport capability of the second region 2 for second carriers. The projection of the second region 2 at least partially overlaps with the projection of the second carrier selection layer 22, thereby facilitating processing. For example, as shown in Figure 4, the overlap between the projection of the second region 2 and the projection of the second carrier selection layer 22 is relatively high.

[0066] The second carrier selection layer 22 is located on the back-lighting or light-facing side of the metal oxidant layer 4. For example, referring to FIG4, the second carrier selection layer 22 is located on the light-facing side of the metal oxidant layer 4. As another example, referring to FIG5, FIG5 shows a schematic diagram of the structure of a fifth back-contact solar cell according to an embodiment of the present invention. The second carrier selection layer 22 is located on the back-lighting side of the metal oxidant layer 4.

[0067] Optionally, referring to Figure 4 or Figure 5, the second carrier selection layer 22 is a single layer or multiple layers, and the thickness d2 of the second carrier selection layer 22 is 1-500 nm, more preferably 2-60 nm. This thickness of the second carrier selection layer 22 is beneficial for the transport of the second carriers.

[0068] Optionally, the area of ​​the projection of the second carrier selection layer 22 onto the back surface of the silicon substrate 1 accounts for 5% to 45% of the total area of ​​the back surface of the silicon substrate 1. This area ratio provides good transport performance for the second carriers without affecting the collection and transport of the first carriers. It should be noted that the area of ​​the second carrier selection layer 22 may be equal to or different from that of the second region 2 described above; this embodiment of the invention does not impose a specific limitation on this.

[0069] Optionally, when the silicon substrate is an n-type silicon substrate and the second charge carriers are majority carriers, or when the silicon substrate is a p-type silicon substrate and the second charge carriers are minority carriers, the material of the second charge carrier selection layer is selected from at least one of the following: a crystalline silicon material with a work function greater than or equal to 3 eV, an amorphous silicon material with a work function greater than or equal to 3 eV, or a second material. The second material is a metal oxometalate compound with a work function greater than or equal to 3 eV. The second charge carrier selection layer made of the above materials exhibits good collection and transport effects on the second charge carriers.

[0070] Optionally, when the silicon substrate is a p-type silicon substrate and the second charge carriers are majority carriers, or when the silicon substrate is an n-type silicon substrate and the second charge carriers are minority carriers, the material of the second charge carrier selective layer can be selected from at least one of the first materials; the first material is an n-type metal oxo compound with a work function greater than or equal to 5 eV, or a p-type metal oxo compound with a work function less than or equal to 6 eV. The second charge carrier selective layer of the above materials has good collection and transport effects on the second charge carriers.

[0071] The specific selection of the second and first materials can be referred to the aforementioned records, and can achieve the same or similar beneficial effects. To avoid repetition, it will not be elaborated here.

[0072] Optionally, a tunneling isolation layer is disposed between the back surface of the silicon substrate and the metal oxide compound layer. The tunneling isolation layer can be a single layer or multiple layers, with a thickness of 0.1 nm to 5 nm. The tunneling isolation layer provides good surface passivation and can reduce current recombination at the interface.

[0073] For example, referring to Figure 6, which shows a schematic diagram of the sixth type of back-contact solar cell in an embodiment of the present invention, a tunneling isolation layer 3 is disposed between the back surface of the silicon substrate 1 and the metal oxide compound layer 4, with a thickness d3 of 0.1 nm-5 nm, based on Figure 2 above. Referring to Figure 7, which shows a schematic diagram of the seventh type of back-contact solar cell in an embodiment of the present invention, the tunneling isolation layer 3 is located between the back surface of the silicon substrate 1 and the light-facing surface of the metal oxide compound layer 4 and the light-facing surface of the second carrier selection layer 22, based on Figure 4 above. As another example, referring to Figure 8, which shows a schematic diagram of the eighth type of back-contact solar cell in an embodiment of the present invention, the tunneling isolation layer 3 is located between the back surface of the silicon substrate 1 and the light-facing surface of the metal oxide compound layer 4 and the light-facing surface of the second carrier selection layer 22.

[0074] Optionally, the material of the tunneling isolation layer is selected from at least one of silicon oxides, silicon nitrides, silicon oxide nitrides, and silicon halides. The above-mentioned materials provide better surface chemical passivation for the tunneling isolation layer. The tunneling isolation layer can be formed independently, for example, using in-situ reaction processes such as wet thermal oxidation or dry thermal oxidation, or using deposition processes such as chemical vapor deposition or physical vapor deposition. Alternatively, it can be integrated with a metal oxometalate layer, such as an interfacial silicon oxide layer formed during the growth of the metal oxometalate or post-annealing process, as the tunneling isolation layer. It should be noted that if the tunneling isolation layer is a silicon-free material, it may include a chemical transition layer between the silicon material and the silicon material.

[0075] Optionally, the material of the tunneling isolation layer can be a dielectric material with a dielectric constant greater than 2. Dielectric materials can be polarized into insulating materials. Choosing a dielectric material with a dielectric constant greater than 2 not only provides good surface chemical passivation but also good field passivation, effectively blocking lateral conductivity.

[0076] Optionally, the breakdown voltage of the tunneling isolation layer is greater than or equal to 3MV / cm, with good surface passivation and good blocking effect on lateral conductivity.

[0077] Optionally, the material of the tunneling isolation layer is selected from: silicon dioxide (such as SiO2). x ), silicon nitride (such as SiN) x Silicon fluoride (e.g., SiF4), silicon oxyfluoride (e.g., SiOF), silicon oxycarbide (e.g., SiOC), aluminum oxide (e.g., Al2O3), aluminum fluoride (e.g., AlF) x At least one of the following: (e.g., aluminum oxynitride, such as AlON). The tunneling isolation layer of the above materials has good surface passivation and provides good blocking effect against lateral conductivity. It should be noted that the value of x in the chemical formula can be selected appropriately by those skilled in the art based on the actual situation.

[0078] Optionally, a second transparent conductive film and / or a second work function adjustment layer are disposed between the second carrier collecting terminal and the second electrode. That is, a second transparent conductive film, a second work function adjustment layer, or both may be disposed between the second carrier collecting terminal and the second electrode. Both the second transparent conductive film and / or the second work function adjustment layer are located within the projection area of ​​the second carrier collecting terminal. It should be noted that, in the case of both, the second transparent conductive film may be located on the back-lighting side or the light-facing side of the second work function adjustment layer. The projection of the second electrode may be located within the projection of the second transparent conductive film and / or the second work function adjustment layer.

[0079] And / or, a first transparent conductive film and / or a first work function adjustment layer are disposed between the first carrier collecting terminal and the first electrode. That is, a first transparent conductive film, or a first work function adjustment layer, or both may be disposed between the first carrier collecting terminal and the first electrode. The first transparent conductive film and / or the first work function adjustment layer are both located within the projection area of ​​the first carrier collecting terminal. It should be noted that, in the case of both, the first transparent conductive film may be located on the back-light side or the light-facing side of the first work function adjustment layer. The projection of the first electrode may be located within the projection of the first transparent conductive film and / or the first work function adjustment layer.

[0080] The first and second transparent conductive films mentioned above can assist in carrier transport and are also transparent, which can further improve photoelectric conversion efficiency. The first and second work function adjustment layers reduce contact resistance.

[0081] Figure 9 shows a schematic diagram of the ninth type of back-contact solar cell according to an embodiment of the present invention. Referring to Figures 5, 8, or 9, a second transparent conductive film 63 and a second work function adjustment layer 62 are disposed between the second carrier collection terminal and the second electrode 6. The second transparent conductive film 63 is located on the light-facing side of the second work function adjustment layer 62. A first transparent conductive film 52 and a first work function adjustment layer 53 are disposed between the first carrier collection terminal and the first electrode 5. The first transparent conductive film 52 is located on the back-facing side of the first work function adjustment layer 53.

[0082] Optionally, referring to Figure 9, the thickness d4 of the second work function adjustment layer 62 and the thickness d5 of the first work function adjustment layer 53 are both 0.1-5 nm. This thickness range can further reduce contact resistance.

[0083] Optionally, the second transparent conductive film is formed by combining or mixing a transparent conductive material and a work function regulating material. And / or, the first transparent conductive film is formed by combining or mixing a transparent conductive material and a work function regulating material. That is, the first and second transparent conductive films not only assist in carrier transport but also transmit light, which can further improve photoelectric conversion efficiency, while reducing contact resistance or longitudinal resistance.

[0084] Optionally, if a second transparent conductive film is provided between the second carrier collection terminal and the second electrode, the second electrode is provided on the back side of the second transparent conductive film in the form of a grid line, which makes full use of the back light transmission and can further improve the photoelectric conversion efficiency.

[0085] And / or, when a first transparent conductive film is provided between the first carrier collection terminal and the first electrode, the first electrode is provided in the form of a grid line on the back surface of the first transparent conductive film, making full use of the back light transmission, which can further improve the photoelectric conversion efficiency.

[0086] Optionally, the materials of both the first and second transparent conductive films are independently selected from at least one of the following: zinc oxide, aluminum-doped zinc oxide, tin oxide, indium-doped tin oxide, and indium-gallium-doped tin oxide. The first and second transparent conductive films made of the above materials exhibit superior carrier transport performance, which can further improve photoelectric conversion efficiency.

[0087] Optionally, the work functions of both the first and second work function adjustment layers are 1eV-5.5eV, which can further reduce the contact resistance.

[0088] Optionally, the materials of the first work function adjustment layer, the second work function adjustment layer, the first transparent conductive film, and / or the work function adjustment material in the second transparent conductive film can all be independently selected from at least one of alkali metals, transition metals, alkali metal halides, or transition metal halides, which can further reduce contact resistance.

[0089] Optionally, the materials of the first work function adjustment layer, the second work function adjustment layer, the first transparent conductive film, and / or the work function adjustment material in the second transparent conductive film can all be independently selected from: Ca, Mg, Ba, LiF. x , KFx, MgF x BaCl x etc. In this chemical formula, those skilled in the art can choose an appropriate value for x based on the actual situation.

[0090] Optionally, the work function of the material in the first transparent conductive film and / or the second transparent conductive film is adjusted to 1eV-5.5eV, which can further reduce the contact resistance.

[0091] Optionally, referring to Figure 1, the second region 2 is doped to form a second carrier collection terminal. The second carrier collection terminal can collect and transport second carriers. It should be noted that the second region 2 and the second region in the silicon substrate 1 have the same doping type, but the doped elements can be the same or different. In this embodiment of the invention, no specific limitation is made in this regard.

[0092] The doping concentration of the second carrier collection terminal can be referred to the aforementioned records, and will not be repeated here to avoid repetition.

[0093] Referring to Figure 1, the metal oxo compound layer 4, serving as the first carrier collection terminal, is deposited only on the first region of the backlight surface of the silicon substrate 1. The first carrier collection terminal can collect and transport the first carriers.

[0094] Referring to Figure 1, the second electrode 6 is disposed on the second carrier collecting terminal, and is used to conduct the second carriers. The first electrode 5 is disposed on the first carrier collecting terminal, and is used to conduct the first carriers. It should be noted that an electrical insulation gap must be maintained between the second electrode 6 and the first electrode 5, and the electrical insulation gap shall not be less than the breakdown distance under normal operating voltage. The second electrode 6 and the first electrode 5 can be fabricated using processes such as printing or deposition. The first electrode 5 and the second electrode 6 can be metal electrodes.

[0095] In Figure 1, the second region 2 of the back surface of the doped silicon substrate 1 achieves the collection and transport of the second charge carriers, while the metal oxide compound layer 4 deposited only in the first region of the back surface of the silicon substrate 1 achieves the collection and transport of the first charge carriers. Different materials located at different positions achieve the collection and transport of different charge carriers, eliminating the need for additional alignment and electrical isolation, simplifying the process, reducing the area of ​​the non-collection region, and improving the photoelectric conversion efficiency. Simultaneously, the second charge carrier collection end is directly connected to the second electrode 6, and the first charge carrier collection end is directly connected to the first electrode 5. Their charge carrier conduction energy levels are close, with no contact barrier or only a very small contact barrier, reducing the longitudinal contact resistance. Furthermore, the second and first charge carrier collection ends and the metal oxide compound layer 4 do not form a reverse pn junction due to mutual contact. Moreover, the structure and performance of the metal oxide compound layer 4 are highly tunable, achieving both low lateral conductivity and strong longitudinal conductivity, with good thermal stability and a wide process selection window.

[0096] Alternatively, referring to Figure 10, which shows a schematic diagram of the tenth type of back-contact solar cell according to an embodiment of the present invention, this back-contact solar cell can also include: a silicon substrate 1, the back surface of which is divided into a first region and a second region 2. The second region 2 of the silicon substrate 1 is doped to form a second carrier collection terminal, as described above; to avoid repetition, it will not be repeated here. As shown in Figure 10, a metal oxide compound layer 4 is deposited on the entire back surface of the silicon substrate 1. Compared to depositing other material layers on the entire back surface of the silicon substrate 1, this method offers greater structural and performance tunability, achieving lower lateral conductivity and stronger longitudinal conductivity, better thermal stability, and a wider process selection window.

[0097] Referring to Figure 10, the portion of the metal oxo compound layer 4 corresponding to the first region of the backlight surface of the silicon substrate 1 forms a first carrier collection terminal, which can collect and transport first carriers. A first electrode 5 is correspondingly disposed on the first carrier collection terminal, with low longitudinal contact resistance.

[0098] Referring to FIG10, at least a portion of the metal oxidant layer 4 corresponding to the second region of the backlight surface of the silicon substrate 1 has an opening that electrically divides the metal oxidant layer 4. This opening can completely or partially cut off the metal oxidant layer 4. A second carrier selection layer 22 is filled in the opening for transporting second carriers. A second electrode 6 is correspondingly disposed on the second carrier selection layer 22. Furthermore, the second carriers are collected by the second electrode 6 via the second carrier selection layer 22. It should be noted that the opening region is approximately equal to the second region, but can be larger or smaller than the second region. The peripheral region of the second carrier selection layer 22 can be larger than the opening region. The opening can completely or partially disconnect the metal oxidant layer 4.

[0099] The second electrode 6 and the first electrode 5 can also be referred to the aforementioned records. To avoid repetition, they will not be repeated here.

[0100] Referring to Figure 1 or Figure 10, if the silicon substrate 1 is an n-type silicon substrate, and the first charge carrier is a hole, and the second charge carrier is an electron, then the second charge carrier collecting end is the electron accumulation region. The second charge carrier collecting end is a doped structure, which can cause the energy band of the n-type silicon substrate to bend downwards in the second region 2, attracting electrons and repelling holes, thus achieving selective electron collection. Referring to Figure 1, the metal oxometalate layer 4 forms the first charge carrier collecting end, which is the hole accumulation region. The first charge carrier collecting end acts as a hole-selective contact material. The conduction band energy level of this material is close to the valence band energy level of the n-type silicon substrate, and it can possess an interface negative charge or negative fixed defects, which can cause the energy band at the interface to bend upwards, forming an interface p-type layer, thus attracting holes and repelling electrons. Alternatively, referring to Figure 10, the portion of the metal oxometalate layer 4 corresponding to the first region forms the first charge carrier collecting end, which is the hole accumulation region. The first carrier collection terminal, corresponding to the first region in the metal oxometalate layer, acts as a hole-selective contact material. The conduction band level of this material is close to the valence band level of the n-type silicon substrate, and it can possess interface negative charges or negative fixed defects, causing the energy band at the interface to bend upwards, forming an interface p-type layer that attracts holes and repels electrons. Referring to Figure 10, the second carrier selection layer 22 has a higher electron density and a lower hole density, resulting in a lower conduction band bottom level, close to the conduction band bottom level of the second carrier collection terminal, thus facilitating electron transport.

[0101] It should be noted that the aforementioned conduction band energy level and valence band energy level generally refer to the energy level of the material itself, that is, the energy level when the material exists alone, and not the actual energy level in the battery structure.

[0102] In Figure 1 or Figure 10, the second carrier collection end adopts a locally doped selective contact structure, and the metal oxo compound layer 4 adopts a deposited selective contact structure. Compared with the traditional fully diffused back contact structure, it has the advantage of low bulk recombination in the minority carrier collection part, and at the same time, it has fewer diffusion steps and a relatively simple process. Compared with the structure using amorphous silicon as the back contact, the metal oxo compound layer 4 has stronger selectivity and higher thermal stability. At the same time, the material deposition process has lower equipment requirements and higher safety.

[0103] The first carrier collection terminal is formed by using the portion of the metal oxo compound layer 4 corresponding to the first region. Compared with amorphous silicon materials, it has stronger selectivity and longitudinal transport capability, and the first carrier collection and longitudinal transport capabilities are stronger.

[0104] In Figure 10, at least the portion of the continuous metal oxidant layer 4 corresponding to the second region 2 has openings that electrically divide the metal oxidant layer 4. These openings are filled with a second carrier selection layer 22. The second electrode 6 is disposed on the second carrier selection layer 22. Essentially, the second carriers are transported specifically through the second carrier selection layer 22, while the first carriers are mainly transported through the un-opened portion of the metal oxidant layer 4. This allows different materials to transport different carriers separately, eliminating the need for additional alignment and electrical isolation, simplifying the process, reducing the area of ​​the non-collection region, and improving photoelectric conversion efficiency. Furthermore, the first and second carriers are transported through different materials, and the second carrier selection layer 22 facilitates the transport of the second carriers, with its carrier conduction energy level being closer to that of the second region 2. The contact between the two regions has no or very small barrier, reducing longitudinal contact resistance. Simultaneously, the second carrier collection end, the first carrier collection end, and the metal oxidant layer 4 do not form a reverse pn junction due to mutual contact. Furthermore, the structure and properties of the metal oxo compound layer 4 are highly tunable, enabling lower lateral conductivity and stronger longitudinal conductivity, while also exhibiting good thermal stability and a wide process selection window.

[0105] Optionally, the projection of the second region 2 at least partially overlaps with the projection of the second carrier selection layer 22, thereby facilitating fabrication. The second carrier selection layer 22 is located on the back or light-facing side of the metal oxidant layer 4. For example, as shown in FIG10, the projection of the second region 2 and the projection of the second carrier selection layer 22 have a high degree of overlap. In FIG10, the second carrier selection layer 22 can be considered to be located on the back surface of the metal oxidant layer 4.

[0106] Optionally, the metal oxo compound layer 4 can be a single layer or multiple layers. Referring to FIG1, the thickness d1 of the metal oxo compound layer 4 is as described above.

[0107] Optionally, the area of ​​the projection of the second carrier selection layer 22 onto the back surface of the silicon substrate 1 accounts for 5% to 45% of the total area of ​​the back surface of the silicon substrate 1. This area ratio provides good transport performance for the second carriers without affecting the collection and transport of the first carriers. It should be noted that the area of ​​the second carrier selection layer 22 may be equal to or different from that of the second region 2 described above; no specific limitation is made in this regard.

[0108] Referring to Figure 11, which shows a schematic diagram of the eleventh back-contact solar cell according to an embodiment of the present invention, a tunneling isolation layer 3 is provided between the back surface of the silicon substrate 1 and the metal oxide layer 4, with a thickness d2 of 0.1 nm-5 nm. The opening can completely or partially disconnect the tunneling isolation layer 3 when the metal oxide layer 4 is completely disconnected. The material of the tunneling isolation layer 3, etc., is as described above.

[0109] Optionally, when the second electrode is correspondingly disposed on the second carrier selection layer, a third transparent conductive film and / or a third work function adjustment layer are disposed between the second carrier selection layer and the second electrode; that is, a third transparent conductive film, a third work function adjustment layer, or both may be disposed between the second carrier selection layer and the second electrode. The third transparent conductive film and / or the third work function adjustment layer are both located within the projected portion of the second carrier selection layer. It should be noted that, in the case of both, the third transparent conductive film may be located on the back-light surface or the light-facing surface of the third work function adjustment layer.

[0110] The third transparent conductive film can assist in carrier transport and is also transparent, which can further improve photoelectric conversion efficiency. The third work function adjustment layer can reduce contact resistance.

[0111] Figure 12 shows a schematic diagram of the twelfth back-contact solar cell according to an embodiment of the present invention. For example, referring to Figure 13, Figure 13 shows a schematic diagram of the thirteenth back-contact solar cell according to an embodiment of the present invention. The difference between Figure 12 and Figure 13 is that in Figure 13, a tunneling isolation layer 3 is disposed between the back surface of the silicon substrate 1 and the metal oxide compound layer 4. Referring to Figure 12 or Figure 13, a first transparent conductive film 52 and a first work function adjustment layer 53 are disposed between the first carrier collection terminal and the first electrode 5. The first transparent conductive film 52 is located on the light-facing side of the first work function adjustment layer 53. Referring to Figure 12 or Figure 13, a third transparent conductive film 65 and a third work function adjustment layer 64 are disposed between the second carrier selection layer 22 and the second electrode 6. The third transparent conductive film 65 is located on the back surface of the third work function adjustment layer 64.

[0112] Optionally, referring to Figure 12, the thickness d6 of the third work function adjustment layer 64 is 0.1-2 nm. This thickness range can further reduce contact resistance.

[0113] Optionally, the third transparent conductive film is formed by combining or mixing transparent conductive materials and work function-adjusting materials. This third transparent conductive film not only assists in carrier transport but also allows light transmission, further improving photoelectric conversion efficiency. Simultaneously, it can reduce contact resistance or longitudinal resistance.

[0114] Optionally, if a third transparent conductive film is disposed between the second carrier selection layer and the second electrode, the second electrode is disposed on the back surface of the third transparent conductive film in the form of a grid line, making full use of the light transmission of the back surface, which can further improve the photoelectric conversion efficiency.

[0115] Optionally, the material of the third transparent conductive film is selected from at least one of the following: zinc oxide, aluminum-doped zinc oxide, tin oxide, indium-doped tin oxide, and indium-gallium-doped tin oxide. The third transparent conductive film made of the above materials exhibits superior carrier transport performance, which can further improve photoelectric conversion efficiency.

[0116] Optionally, the work function of the third work function adjustment layer is 1eV-5.5eV, which can further reduce the contact resistance.

[0117] Optionally, the material of the third work function adjustment layer and / or the work function adjustment material in the third transparent conductive film can be independently selected from at least one of alkali metals, transition metals, alkali metal halides, or transition metal halides, which can further reduce the contact resistance.

[0118] Optionally, the material of the third work function adjustment layer and / or the work function adjustment material in the third transparent conductive film can be independently selected from: Ca, Mg, Ba, LiF.x , KFx, MgF x BaCl x etc. In the chemical formula, those skilled in the art can choose an appropriate value for x based on the actual situation.

[0119] Optionally, the work function of the material in the third transparent conductive film can be adjusted to 1eV-5.5eV, which can further reduce the contact resistance.

[0120] Optionally, the light-facing surface of the silicon substrate may also be provided with at least one of the following: a passivation layer, a front-side field-effect layer, a front-side anti-reflection film layer, a scattering structure layer, and a light-concentrating structure layer. And / or, when the second electrode is correspondingly disposed on the second carrier collection terminal, a back-side anti-reflection film is provided on the back-facing surface of the metal oxidant layer, in the portion outside the second electrode, and in the portion outside the second electrode in the second region. And / or, when the second electrode is correspondingly disposed on the second carrier selection layer, a back-side anti-reflection film is provided on the back-facing surface of the metal oxidant layer and the back-facing surface of the second carrier selection layer, in the portion outside the second electrode, to achieve passivation, optical improvement, etc.

[0121] For example, as shown in Figures 10 to 13, 7 can be the front anti-reflection film layer, and 8 can be the back anti-reflection film layer.

[0122] Optionally, the second carrier selection layer can be a single layer or multiple layers. The thickness of the second carrier selection layer is independent of the thickness of the metal oxometalate layer, and the thickness of the second carrier selection layer 22 can be slightly greater than the height of the aperture. For example, the thickness of the second carrier selection layer is 1-500 nm, and more preferably, the thickness of the second carrier selection layer is 2-60 nm. This thickness of the second carrier selection layer 22 is beneficial for the transport of the first carriers.

[0123] Optionally, when the silicon substrate is an n-type silicon substrate and the second charge carriers are majority carriers, or when the silicon substrate is a p-type silicon substrate and the second charge carriers are minority carriers, the material of the second charge carrier selection layer is selected from at least one of the following: a crystalline silicon material with a work function greater than or equal to 3 eV, an amorphous silicon material with a work function greater than or equal to 3 eV, or a second material. The second material is a metal oxometalate layer with a work function greater than or equal to 3 eV. The second charge carrier selection layer made of the above materials exhibits good collection and transport effects on the second charge carriers.

[0124] Optionally, when the silicon substrate is a p-type silicon substrate and the second charge carriers are majority carriers, or when the silicon substrate is an n-type silicon substrate and the second charge carriers are minority carriers, the material of the second charge carrier selection layer can be selected from at least one of the first materials; the first material is an n-type metal oxo compound layer with a work function greater than or equal to 5 eV, or a p-type metal oxo compound layer with a work function less than or equal to 6 eV. The second charge carrier selection layer of the above materials has good collection and transport effects on the second charge carriers.

[0125] The specific selection of the second and first materials can be referred to the aforementioned records, and can achieve the same or similar beneficial effects. To avoid repetition, it will not be elaborated here.

[0126] Optionally, referring to Figure 14, which shows a schematic diagram of the fourteenth back-contact solar cell according to an embodiment of the present invention, the second region 2 is doped to form a second carrier collection terminal. The second carrier collection terminal can realize the collection and transport of second carriers. It should be noted that the second region 2 and the second region in the silicon substrate 1 have the same doping type, but the doped elements can be the same or different. In this embodiment of the present invention, no specific limitation is made in this regard.

[0127] In Figure 14, a metal oxide compound layer 4 is deposited on the back surface of the entire silicon substrate 1. Compared with the deposition of other material layers on the back surface of the entire silicon substrate 1, it has strong structural and performance adjustability, can achieve lower lateral conductivity and stronger longitudinal conductivity, and has better thermal stability and a wider process selection window.

[0128] In Figure 14, the metal oxidant layer 4 has a blocking structure 9 that electrically divides the metal oxidant layer 4 into a second carrier transport region and a first carrier collection terminal. The number of blocking structures 9 is not specifically limited. The first carrier collection terminal is located in the portion corresponding to the first region of the backlight surface of the silicon substrate 1, and the first carrier collection terminal can collect and transport first carriers. The second carrier transport region is located in the portion corresponding to the second region of the backlight surface of the silicon substrate 1, and the second carrier transport region can transport second carriers.

[0129] A first electrode 5 is provided at the first carrier collection terminal, and the first electrode 5 is used to conduct the first carriers. A second electrode 6 is provided at the second carrier transport region, and the second electrode 6 is used to conduct the second carriers. It should be noted that an electrical insulation gap must be maintained between the first electrode 5 and the second electrode 6, and the electrical insulation gap shall not be less than the breakdown distance under normal operating voltage. The first electrode 5 and the second electrode 6 can be fabricated using processes such as printing and deposition. The second electrode 6 and the first electrode 5 can be metal electrodes.

[0130] Referring to Figure 14, if the silicon substrate 1 is an n-type silicon substrate, and the first charge carrier is a hole, and the second charge carrier is an electron, then the second charge carrier collection terminal is the electron collection region. The second charge carrier collection terminal has a doped structure, which can cause the energy band of the n-type silicon substrate to bend downwards in this second region 2, attracting electrons and repelling holes, thus achieving selective electron collection. The first charge carrier collection terminal is the hole collection region. The first charge carrier collection terminal acts as a hole-selective contact material. The conduction band energy level of this material is close to the valence band energy level of the n-type silicon substrate, and it can possess a negative interface charge or negative fixed defects, which can cause the energy band at the interface to bend upwards, forming a p-type interface layer, thus attracting holes and repelling electrons.

[0131] It should be noted that the aforementioned conduction band energy level and valence band energy level generally refer to the energy level of the material itself, that is, the energy level when the material exists alone, and not the actual energy level in the battery structure.

[0132] In Figure 14, the electron density is high and the hole density is low in the second carrier transport region, resulting in a low conduction band bottom energy level that is close to the conduction band bottom energy level of the second carrier collection end. Therefore, electrons can directly enter the second carrier transport region in the metal oxo compound layer corresponding to the second carrier collection end, thereby realizing electron transport.

[0133] In Figure 14, if the silicon substrate 1 is an n-type silicon substrate, and the first charge carrier is a hole and the second charge carrier is an electron, the two parts electrically separated by the blocking structure 9 in the metal oxo compound layer 4 can respectively realize the collection of holes and the transport of electrons. At the same time, the material can be made to have low lateral conductivity by adjusting the crystallinity, crystal phase and doping elements. Due to the electrical separation of the blocking structure 9, the holes in the first charge carrier collection end and the electrons in the second charge carrier transport region are longitudinally transported into the corresponding electrodes after being collected, and will not be interconnected due to lateral transport, resulting in leakage or short circuit. Therefore, the collection ends of different types of charge carriers do not need to be electrically isolated, and will not generate a reverse pn junction due to mutual contact.

[0134] In Figure 14, the second carrier collection end adopts a locally doped selective contact structure, and the metal oxide layer 4 adopts a deposited selective contact structure. Compared with the traditional fully diffused back contact structure, it has the advantages of low bulk recombination, fewer diffusion steps, and a relatively simpler process. Compared with the structure using amorphous silicon as the back contact, the metal oxide layer 4 has stronger selectivity, higher thermal stability, and lower equipment requirements for the material deposition process, resulting in higher safety. The metal oxide layer 4 can fully cover the back of the battery, further simplifying the process flow.

[0135] In Figure 14, the portion of the metal oxo compound layer 4 corresponding to the first region is used to form the first carrier collection end. Compared with amorphous silicon material, it has stronger selectivity and longitudinal transport capability. The first carrier collection and longitudinal transport capability are stronger, and lower contact resistance can be achieved. At the same time, in the second carrier collection end, in conjunction with the localized doping structure, the second carrier transport is carried out through the band edge of the oxide material, without involving the cross-level tunneling mechanism. The second carrier transport has less resistance, and lower contact resistance can be achieved.

[0136] Optionally, the blocking structure is a slotted structure; and / or, the blocking structure is an insulator. The above-mentioned blocking structures not only have good blocking effects but also simple implementation processes. For example, the insulator can be set using ion implantation.

[0137] Optionally, the thickness of the blocking structure is greater than or equal to the thickness of the metal oxometalate layer, resulting in better electrical blocking performance. For example, referring to FIG14, the thickness of the blocking structure 9 is equal to the thickness of the metal oxometalate layer 4. When the thickness of the blocking structure is greater than the thickness of the metal oxometalate layer, the blocking structure protrudes towards the back surface of the metal oxometalate layer.

[0138] For example, as shown in FIG15, based on FIG14 above, the thickness of the blocking structure 9 is greater than the thickness of the metal oxo compound layer 4, and the blocking structure 9 protrudes toward the backlight surface of the metal oxo compound layer 4.

[0139] Referring to Figure 16, which shows a schematic diagram of the sixteenth type of back-contact solar cell according to an embodiment of the present invention. Based on Figure 14 above, 7 in Figure 16 can be a front anti-reflection thin film layer, and 8 can be a back anti-reflection film.

[0140] Referring to Figure 17, which shows a schematic diagram of the seventeenth back-contact solar cell according to an embodiment of the present invention, a tunneling isolation layer 3 is provided between the back surface of the silicon substrate 1 and the metal oxide compound layer 4, and the thickness of the tunneling isolation layer 3 is 0.1 nm-5 nm. The material of the tunneling isolation layer 3 is as described above.

[0141] Optionally, a fourth transparent conductive film and / or a fourth work function adjustment layer are disposed between the second carrier transport region and the second electrode. That is, a fourth transparent conductive film, a fourth work function adjustment layer, or both can be disposed between the second carrier transport region and the second electrode. Both the fourth transparent conductive film and / or the fourth work function adjustment layer are located within the projection area of ​​the second carrier transport region. It should be noted that, in the case of both, the fourth transparent conductive film can be located on the back-lighting side or the light-facing side of the fourth work function adjustment layer. The projection of the second electrode can be located within the projection of the fourth transparent conductive film and / or the fourth work function adjustment layer.

[0142] The fourth transparent conductive film assists in carrier transport and is also transparent, further improving photoelectric conversion efficiency. The fourth work function adjustment layer reduces contact resistance.

[0143] Figure 18 shows a schematic diagram of the eighteenth back-contact solar cell according to an embodiment of the present invention. Referring to Figure 18, a fourth transparent conductive film 67 and a fourth work function adjustment layer 66 are disposed between the second carrier transport region and the second electrode 6. The fourth transparent conductive film 67 is located on the back surface of the fourth work function adjustment layer 66. A first transparent conductive film 52 and a first work function adjustment layer 53 are disposed between the first carrier collection terminal and the first electrode 5. The first transparent conductive film 52 is located on the back surface of the first work function adjustment layer 53.

[0144] Optionally, as shown in FIG18, the thickness d7 of the fourth transparent conductive film 67 is 0.1-2nm, which can further reduce the contact resistance.

[0145] Optionally, the fourth transparent conductive film is formed by combining or mixing a transparent conductive material and a work function regulating material. And / or, the first transparent conductive film is formed by combining or mixing a transparent conductive material and a work function regulating material. That is, the first and fourth transparent conductive films not only assist in carrier transport but also transmit light, which can further improve photoelectric conversion efficiency, while reducing contact resistance or longitudinal resistance.

[0146] Optionally, if a fourth transparent conductive film is provided between the second carrier transport region and the second electrode, the second electrode is provided on the back side of the fourth transparent conductive film in the form of a grid line, making full use of the back light transmission, which can further improve the photoelectric conversion efficiency.

[0147] And / or, when a first transparent conductive film is provided between the first carrier collection terminal and the first electrode, the first electrode is provided in the form of a grid line on the back surface of the first transparent conductive film, making full use of the back light transmission, which can further improve the photoelectric conversion efficiency.

[0148] Optionally, the material of the fourth transparent conductive film is selected from at least one of the following: zinc oxide, aluminum-doped zinc oxide, tin oxide, indium-doped tin oxide, and indium-gallium-doped tin oxide. The fourth transparent conductive film made of the above materials has better carrier transport performance, which can further improve the photoelectric conversion efficiency.

[0149] Optionally, the work function of the fourth work function adjustment layer is 1eV-5.5eV, which can further reduce the contact resistance.

[0150] Optionally, the material of the fourth work function adjustment layer and the work function adjustment material in the fourth transparent conductive film can be independently selected from at least one of alkali metals, transition metals, alkali metal halides, or transition metal halides, which can further reduce the contact resistance.

[0151] Optionally, the material for the fourth work function adjustment layer and the work function adjustment material in the fourth transparent conductive film can be independently selected from: Ca, Mg, Ba, LiF. x , KFx, MgF x BaCl x etc. In the chemical formula, those skilled in the art can choose an appropriate value for x based on the actual situation.

[0152] Optionally, the work function of the material of the fourth work function adjustment layer and / or the work function adjustment material in the fourth transparent conductive film is 1eV-5.5eV, which can further reduce the contact resistance.

[0153] Optionally, referring to Figure 19, which shows a schematic diagram of the nineteenth type of back-contact solar cell according to an embodiment of the present invention, a second carrier selective collection layer 23 is deposited on a second region of the back surface of the silicon substrate 1. The second carrier selective collection layer 23 can collect and transport second carriers. A metal oxide compound layer 4 is deposited on the common back surface of the silicon substrate 1 and the second carrier selective collection layer 23. The metal oxide compound layer 4 has strong structural and performance tunability, can achieve lower lateral conductivity and stronger longitudinal conductivity, and has good thermal stability and a wide process selection window.

[0154] The portion of the metal oxidant layer 4 corresponding to the second carrier selective collection layer 23 forms a second carrier transport region, enabling the transport of the second carriers. The portion of the metal oxidant layer 4 corresponding to the first region of the silicon substrate 1 forms a first carrier collection terminal, enabling the collection and transport of the first carriers.

[0155] Optionally, the area of ​​the projection of the second carrier selective collection layer 23 onto the back surface of the silicon substrate 1 accounts for 5% to 45% of the total area of ​​the back surface of the silicon substrate. At this area ratio, the collection and transport of the second carriers are effective, while not affecting the collection and transport of the first carriers.

[0156] Optionally, the top view of the second carrier selection and collection layer 23 can be a dotted or line pattern. Dotted patterns can be, for example, circular or elliptical. Line patterns can be, for example, rectangular or polygonal. Having a dotted or line pattern in the top view of the second carrier selection and collection layer 23 simplifies the deposition process.

[0157] A first electrode 5 is disposed on the backlight surface of the first carrier collection end in the metal oxometalate layer 4, and the first electrode 5 is used to conduct the first carriers. A second electrode 6 is disposed on the second carrier transport region, and the second electrode 6 is used to conduct the first carriers. It should be noted that an electrical insulation gap must be maintained between the first electrode 5 and the second electrode 6, and the electrical insulation gap gap is not less than the breakdown distance under normal operating voltage. The first electrode 5 and the second electrode 6 can be fabricated using processes such as printing and deposition. The second electrode 6 and the first electrode 5 can be metal electrodes.

[0158] Referring to Figure 19, if the silicon substrate 1 is an n-type silicon substrate, and the second charge carrier is an electron, and the first charge carrier is a hole, then the second charge carrier selective collection layer 23 is the electron collection terminal. The second charge carrier selective collection layer is a deposited structure, and its conduction band level is close to that of the silicon material. This causes the n-type silicon substrate to bend downwards in the energy band of the second charge carrier selective collection layer 23, attracting electrons and repelling holes, thus achieving selective electron collection. The portion of the metal oxometalate layer 4 corresponding to the first region of the silicon substrate 1 forms the first charge carrier collection terminal, which is the hole collection terminal. The first charge carrier collection terminal acts as a hole-selective contact material. The conduction band level of this material is close to that of the valence band of the n-type silicon substrate, and it can possess an interface negative charge or negative fixed defects. This causes the energy band at the interface to bend upwards, forming an interface p-type layer, which attracts holes and repels electrons.

[0159] It should be noted that the conduction band energy level and valence band energy level in this invention generally refer to the energy level of the material itself, that is, the energy level when the material exists alone, and not the actual energy level in the battery structure.

[0160] In Figure 19, in the second carrier transport region, the bottom conduction band level of the second carrier selective collection layer 23 is located between the conduction band level of the silicon substrate 1 and the conduction band level of the metal oxidant layer 4. Therefore, electrons in the silicon substrate 1 can directly and sequentially enter the second carrier selective collection layer 23 and then enter the second carrier transport region in the metal oxidant layer 4 corresponding to the second carrier selective collection layer 23, thereby realizing electron transport.

[0161] In Figure 19, the metal oxo compound layer 4 can simultaneously collect holes and transport electrons. At the same time, there is a high-resistivity defect at the interface between the second carrier transport region and the first carrier collection end in the metal oxo compound layer 4, which can achieve insulation. After different types of carriers are collected, they are all transported longitudinally into the corresponding electrodes without leakage or short circuit. Therefore, different types of carrier collection ends do not need to be electrically isolated, and they will not generate reverse pn junctions due to mutual contact.

[0162] In Figure 19, the second carrier selective collection layer adopts a deposited selective contact structure, and the metal oxide compound layer 4 also adopts a deposited selective contact structure. Compared with the traditional fully diffused structure, it has the advantages of low bulk recombination, is not limited by the Auger recombination limit, and has fewer diffusion steps, making the process relatively simple. Moreover, both the formation of the second carrier selective collection layer and the metal oxide compound layer are achieved through deposition, eliminating the need for high temperatures. Compared with structures using amorphous silicon, the metal oxide compound layer 4 exhibits stronger selectivity, higher thermal stability, and lower equipment requirements for the material deposition process, resulting in higher safety. The metal oxide compound layer 4 can fully cover the back of the battery, further simplifying the process flow.

[0163] The first carrier collection terminal is formed by using a portion of the first region of the metal oxo compound layer 4 corresponding to the silicon substrate 1. Compared with amorphous silicon materials, it has stronger selectivity and longitudinal transport capability, and the first carrier collection and longitudinal transport capabilities are stronger.

[0164] Optionally, referring to Figure 20, which shows a schematic diagram of the twentieth back-contact solar cell in an embodiment of the present invention, a blocking structure 9 is provided between the second carrier transport region and the first carrier collection terminal in the metal oxide layer 4. This blocking structure 9 electrically separates the second carrier transport region and the first carrier collection terminal in the metal oxide layer, thereby improving the conductivity of the metal oxide compound in the unsegmented region and significantly reducing the longitudinal series resistance. Furthermore, by electrically separating the second carrier transport region and the first carrier collection terminal through the blocking structure, different types of carriers are collected and transported longitudinally into their respective electrodes, preventing leakage or short circuits caused by lateral transport. Therefore, no additional alignment and electrical isolation are required, simplifying the process, reducing recombination, and improving photoelectric conversion efficiency.

[0165] Optionally, the blocking structure can be slotted; and / or, the blocking structure can be a high-resistivity body, the resistivity of which is more than 100 times that of the metal oxometalate layer 4. This provides good insulation performance and simplifies the manufacturing process.

[0166] Optionally, the light-facing surface of the silicon substrate may also be provided with at least one of the following: a passivation layer, a front field-effect layer, a front anti-reflection film layer, a scattering structure layer, and a light-concentrating structure layer. And / or, in the back-facing surfaces of both the metal oxide compound layer and the second carrier transport region, a back anti-reflection film may be provided in the area outside the first and second electrodes to achieve passivation, optical improvement, etc.

[0167] Referring to Figure 21, which shows a schematic diagram of the structure of the twenty-first back-contact solar cell according to an embodiment of the present invention, 7 in Figure 21 can be the front anti-reflection film layer, and 8 can be the back anti-reflection film.

[0168] Optionally, referring to Figure 19, the thickness d8 of the second carrier selective collection layer 23 is 1-500 nm, more preferably 2-60 nm. This thickness of the second carrier selective collection layer 23 is beneficial for the collection and transport of the second carriers.

[0169] Optionally, when the silicon substrate is an n-type silicon substrate and the second charge carriers are majority carriers, or when the silicon substrate is a p-type silicon substrate and the second charge carriers are minority carriers, the material of the second charge carrier selective collection layer is selected from at least one of the following: a crystalline silicon material with a work function greater than or equal to 3 eV, an amorphous silicon material with a work function greater than or equal to 3 eV, or a second material. The second material is a metal oxometalate compound with a work function greater than or equal to 3 eV. The second charge carrier selective collection layer made of the above materials exhibits good collection and transport performance for the second charge carriers.

[0170] Optionally, when the silicon substrate is a p-type silicon substrate and the second charge carriers are majority carriers, or when the silicon substrate is an n-type silicon substrate and the second charge carriers are minority carriers, the material of the second charge carrier selective collection layer can be selected from at least one of the first materials; the first material is an n-type metal oxo compound with a work function greater than or equal to 5 eV, or a p-type metal oxo compound with a work function less than or equal to 6 eV. The second charge carrier selective collection layer of the above materials has good collection and transport effects on the second charge carriers.

[0171] The specific selection of the second and first materials can be referred to the aforementioned records, and can achieve the same or similar beneficial effects. To avoid repetition, it will not be elaborated here.

[0172] Optionally, a tunneling isolation layer is disposed between the back surface of the silicon substrate and the light-facing surface shared by the metal oxo compound layer and the second carrier selective collection layer. The material, thickness, and function of the tunneling isolation layer can be referred to the foregoing description.

[0173] Referring to Figure 22, which shows a schematic diagram of the structure of the twenty-second type of back-contact solar cell in this embodiment of the invention, a tunneling isolation layer 3 is disposed between the back surface of the silicon substrate 1 and the light-facing surface shared by the metal oxide compound layer 4 and the second carrier selective collection layer 23.

[0174] Optionally, a fifth transparent conductive film and / or a fifth work function adjustment layer are disposed between the second electrode and the second carrier selective collection layer. That is, a fifth transparent conductive film, a fifth work function adjustment layer, or both can be disposed between the second electrode and the second carrier selective collection layer. Both the fifth transparent conductive film and / or the fifth work function adjustment layer are located within the projection area of ​​the second carrier selective collection layer. It should be noted that, in the case of both, the fifth transparent conductive film can be located on the back-lighting side or the light-facing side of the fifth work function adjustment layer. The projection of the second electrode can be located within the projection of the fifth transparent conductive film and / or the fifth work function adjustment layer.

[0175] And / or, a first transparent conductive film and / or a first work function adjustment layer are disposed between the first carrier collecting terminal and the first electrode. That is, a first transparent conductive film, or a first work function adjustment layer, or both may be disposed between the first carrier collecting terminal and the first electrode. The first transparent conductive film and / or the first work function adjustment layer are both located within the projection areas of the first carrier collecting terminal and the first electrode. It should be noted that, in the case of both, the first transparent conductive film may be located on the back-light side or the light-facing side of the first work function adjustment layer. The projection of the first electrode may be located within the projection of the first transparent conductive film and / or the first work function adjustment layer.

[0176] Among them, the fifth and first transparent conductive films can assist in carrier transport and are also transparent, which can further improve the photoelectric conversion efficiency. The first and fifth work function adjustment layers reduce contact resistance.

[0177] Figure 23 shows a schematic diagram of the structure of the twenty-third type of back-contact solar cell according to an embodiment of the present invention. Referring to Figure 23, a fifth transparent conductive film 69 and a fifth work function adjustment layer 68 are disposed between the second carrier selective collection layer 23 and the second electrode 6. The fifth transparent conductive film 69 is located on the light-facing side of the fifth work function adjustment layer 68. A first transparent conductive film 52 and a first work function adjustment layer 53 are disposed between the first carrier collection terminal and the first electrode 5. The first transparent conductive film 52 is located on the back-facing side of the first work function adjustment layer 53.

[0178] Optionally, referring to Figure 23, the thickness d9 of the fifth work function adjustment layer 68 is 0.1-2 nm. This thickness range can further reduce contact resistance.

[0179] Optionally, the fifth transparent conductive film is formed by combining or mixing a transparent conductive material and a work function regulating material. And / or, the first transparent conductive film is formed by combining or mixing a transparent conductive material and a work function regulating material. That is, the fifth transparent conductive film and the first transparent conductive film can not only assist in the transport of charge carriers, but also transmit light, which can further improve the photoelectric conversion efficiency, while reducing contact resistance or longitudinal resistance.

[0180] Optionally, if a fifth transparent conductive film is provided between the second carrier selective collection layer and the second electrode, the second electrode is provided on the back side of the fifth transparent conductive film in the form of a grid line, making full use of the back light transmission, which can further improve the photoelectric conversion efficiency.

[0181] And / or, when a first transparent conductive film is disposed between the first electrode and the first carrier collection terminal, the first electrode is disposed on the back side of the first transparent conductive film in the form of a grid line, making full use of the back light transmission, which can further improve the photoelectric conversion efficiency.

[0182] Optionally, the material of the fifth transparent conductive film is selected from at least one of the following: zinc oxide, aluminum-doped zinc oxide, tin oxide, indium-doped tin oxide, and indium-gallium-doped tin oxide. The fifth transparent conductive film made of the above materials has better carrier transport performance, which can further improve the photoelectric conversion efficiency.

[0183] Optionally, the work function of the fifth work function adjustment layer is 1eV-5.5eV, which can further reduce the contact resistance.

[0184] Optionally, the work function adjustment materials in the fifth work function adjustment layer and the fifth transparent conductive film can be independently selected from at least one of alkali metals, transition metals, alkali metal halides, or transition metal halides, which can further reduce the contact resistance.

[0185] Optionally, the work function adjustment materials in the fifth work function adjustment layer and the fifth transparent conductive film can be independently selected from: Ca, Mg, Ba, LiF. x , KFx, MgF x BaCl x etc. In the chemical formula, those skilled in the art can choose an appropriate value for x based on the actual situation.

[0186] Optionally, the work function of the fifth transparent conductive film can be adjusted to 1eV-5.5eV, which can further reduce the contact resistance.

[0187] This invention also provides a method for producing a back-contact solar cell, the method comprising the following steps:

[0188] Step S1: Provide a silicon substrate; the backlight surface of the silicon substrate is divided into a first region and a second region.

[0189] Step S2, at least in the first region of the silicon substrate, a metal oxidant compound layer is deposited; the metal oxidant compound layer and the region corresponding to the first region form a first carrier collection terminal.

[0190] Step S3: A first electrode is disposed on the first carrier collection end; the metal oxo compound layer and the region corresponding to the second region form a second carrier transport region.

[0191] Step S4: Set a second electrode in the region corresponding to the second region.

[0192] Optionally, before step S2, the method may further include: doping the silicon substrate in the second region to form a second carrier collection terminal. Step S2 may include: depositing a metal oxidant compound layer on the back surface of the entire silicon substrate; the metal oxidant compound layer and the region corresponding to the second region form a second carrier transport region. Step S4 includes: correspondingly disposing a second electrode on the second carrier transport region.

[0193] The silicon substrate, second carrier collection terminal, first carrier collection terminal, second carrier transport region, second electrode, and first electrode in each step of this method can be referred to the aforementioned relevant records and can achieve the same or similar beneficial effects. To avoid repetition, they will not be described again here.

[0194] This invention also provides a back-contact solar cell assembly, comprising any of the aforementioned back-contact solar cells. The silicon substrate, second carrier collection terminal, first carrier collection terminal, second carrier transport region, second electrode, and first electrode in this assembly can be specifically described in the foregoing descriptions and can achieve the same or similar beneficial effects; therefore, to avoid repetition, they will not be repeated here.

[0195] The embodiments of the present invention have been described above with reference to the accompanying drawings. However, the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of the present invention without departing from the spirit and scope of the claims. All of these forms are within the protection scope of the present invention.

[0196] The terms "an embodiment," "embodiment," or "one or more embodiments" as used herein mean that a particular feature, structure, or characteristic described in connection with an embodiment is included in at least one embodiment of the invention. Furthermore, please note that the examples of the phrase "in one embodiment" do not necessarily all refer to the same embodiment.

[0197] Numerous specific details are set forth in the specification provided herein. However, it will be understood that embodiments of the invention may be practiced without these specific details. In some instances, well-known methods, structures, and techniques have not been shown in detail so as not to obscure the understanding of this specification.

[0198] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A back-contact solar cell, characterized in that, include: A silicon substrate, wherein the backlight surface of the silicon substrate is divided into a first region and a second region; A metal oxometalate layer is deposited at least in the first region of the silicon substrate; The metal oxo compound layer and the region corresponding to the first region form a first carrier collection terminal; The first electrode is correspondingly disposed on the first carrier collection terminal; The second electrode is disposed in the region corresponding to the second region.

2. The back-contact solar cell according to claim 1, characterized in that, The silicon substrate in the second region is doped to form a second carrier collection terminal; The metal oxidant compound layer is deposited on the entire back surface of the silicon substrate; the metal oxidant compound layer and the region corresponding to the second region form a second carrier transport region; The second electrode is disposed on the second carrier transport region.

3. The back-contact solar cell according to claim 1, characterized in that, The silicon substrate in the second region is doped to form a second carrier collection terminal; The metal oxo compound layer is deposited only on the first region; The second electrode is correspondingly disposed on the second carrier collection terminal; or, The metal oxidant compound layer is deposited on the back surface of the entire silicon substrate; at least a portion of the metal oxidant compound layer corresponding to the second region has an opening that electrically divides the metal oxidant compound layer; a second carrier selection layer is formed on the portion of the metal oxidant compound layer corresponding to the second region, and the second carrier selection layer fills the opening; The second electrode is disposed on the second carrier selection layer.

4. The back-contact solar cell according to claim 1, characterized in that, The silicon substrate in the second region is doped to form a second carrier collection terminal; The metal oxidant compound layer is deposited on the back surface of the entire silicon substrate; the metal oxidant compound layer has a blocking structure that electrically divides the metal oxidant compound layer into a second carrier transport region and a first carrier collection end; wherein the second carrier transport region corresponds to the second region; The second electrode is disposed on the second carrier transport region.

5. The back-contact solar cell according to claim 1, characterized in that, Also includes: A second carrier selection and collection layer; the second carrier selection and collection layer is deposited on the second region of the silicon substrate; The metal oxidant compound layer is deposited on the first region and the backlight surface of the second carrier selective collection layer; the portion of the metal oxidant compound layer corresponding to the second carrier selective collection layer forms a second carrier transport region; The second electrode is disposed on the second carrier transport region.

6. The back-contact solar cell according to any one of claims 2-5, characterized in that, When the silicon substrate is an n-type silicon substrate and the second charge carrier is a majority carrier, or when the silicon substrate is a p-type silicon substrate and the second charge carrier is a minority carrier, the material of the metal oxo compound layer is selected from at least one of the first materials; the first material is an n-type metal oxo compound with a work function greater than or equal to 5 eV, or a p-type metal oxo compound with a work function less than or equal to 6 eV. When the silicon substrate is a p-type silicon substrate and the second charge carrier is a majority carrier, or when the silicon substrate is an n-type silicon substrate and the second charge carrier is a minority carrier, the material of the metal oxo compound layer is selected from at least one of the second materials; the second material is a metal oxo compound with a work function greater than or equal to 3 eV.

7. The back-contact solar cell according to any one of claims 2-4, characterized in that, The doping concentration at the second carrier collection terminal is greater than or equal to 10. 15 cm -3 And greater than the doping concentration of the silicon substrate in the first region; The area of ​​the projection of the second carrier collection terminal onto the back surface of the silicon substrate accounts for 5% to 45% of the total area of ​​the back surface of the silicon substrate.

8. The back-contact solar cell according to any one of claims 2-5, characterized in that, The second region has a second carrier selection layer deposited on its back side; the second carrier selection layer is located on the back side or the light-facing side of the metal oxo compound layer.

9. The back-contact solar cell according to claim 8, characterized in that, The thickness of the second carrier selection layer is 1-500 nm; The area of ​​the projection of the second carrier selection layer onto the back surface of the silicon substrate accounts for 5% to 45% of the total area of ​​the back surface of the silicon substrate.

10. The back-contact solar cell according to claim 8, characterized in that, When the silicon substrate is an n-type silicon substrate and the second charge carrier is a majority carrier, or when the silicon substrate is a p-type silicon substrate and the second charge carrier is a minority carrier, the material of the second charge carrier selection layer is selected from at least one of crystalline silicon material with a work function greater than or equal to 3 eV, amorphous silicon material with a work function greater than or equal to 3 eV, or a second material; the second material is a metal oxo compound with a work function greater than or equal to 3 eV. When the silicon substrate is a p-type silicon substrate and the second charge carrier is a majority carrier, or when the silicon substrate is an n-type silicon substrate and the second charge carrier is a minority carrier, the material of the second charge carrier selection layer is selected from at least one of the first materials; the first material is an n-type metal oxo compound with a work function greater than or equal to 5 eV, or a p-type metal oxo compound with a work function less than or equal to 6 eV.

11. The back-contact solar cell according to claim 6 or 10, characterized in that, The metal oxometalate contains a dopant element, which is selected from at least one of halogen elements, transition metal elements, alkali metal elements, group III elements, group IV elements, and group V elements.

12. The back-contact solar cell according to claim 6 or 10, characterized in that, The second material is selected from at least one of the following: zinc oxide, tin oxide, titanium oxide, copper oxide, thallium oxide, cadmium sulfide, molybdenum sulfide, zinc sulfide, molybdenum selenide, copper selenide, niobium-doped copper oxide, cadmium germanium oxide, zinc iridium oxide, and cobalt calcium oxide; The first material is selected from at least one of the following: molybdenum oxide, tungsten oxide, vanadium oxide, niobium oxide, nickel oxide, mercury-doped niobium oxide, and mercury-doped tantalum oxide.

13. The back-contact solar cell according to claim 2, characterized in that, The lateral conductivity of the metal oxo compound layer is less than or equal to 1.0 × 10⁻⁶. -3 S / cm.

14. The back-contact solar cell according to claim 2, characterized in that, When the silicon substrate is a p-type silicon substrate and the second charge carrier is a majority carrier, or when the silicon substrate is an n-type silicon substrate and the second charge carrier is a minority carrier, The fixed positive charge density of the metal oxidant layer is greater than or equal to 10. 11 cm -2 ; And / or, the acceptor defect density of the metal oxometalate layer is greater than or equal to 10. 11 cm -2 ; And / or, the site charge density of the metal oxometalate layer is greater than or equal to 10. 11 cm -2 ; When the silicon substrate is an n-type silicon substrate and the second charge carrier is a majority carrier, or when the silicon substrate is a p-type silicon substrate and the second charge carrier is a minority carrier, The fixed negative charge density of the metal oxidant layer is greater than or equal to 10. 12 m -2 ; And / or, the donor defect density of the metal oxometalate layer is greater than or equal to 10. 12 cm -2 ; And / or, the site charge density of the metal oxometalate layer is greater than or equal to 10. 12 cm -2 .

15. The back-contact solar cell according to any one of claims 2-5, characterized in that, The metal oxometalate layer has an average transmittance of 70% or more in the visible light band; The thickness of the metal oxo compound layer is 1-600 nm.

16. The back-contact solar cell according to any one of claims 2-5, characterized in that, A tunneling isolation layer is disposed between the back surface of the silicon substrate and the metal oxide compound layer; the thickness of the tunneling isolation layer is 0.1nm-5nm, and the tunneling isolation layer is a single layer or multiple layers.

17. The back-contact solar cell according to claim 16, characterized in that, The material of the tunneling isolation layer is selected from at least one of silicon oxides, silicon nitrides, silicon oxynitrides, and silicon halides.

18. The back-contact solar cell according to claim 16, characterized in that, The tunneling isolation layer is made of a dielectric material, and the dielectric constant of the tunneling isolation layer is greater than 2. The breakdown voltage of the tunneling isolation layer is greater than or equal to 3MV / cm.

19. The back-contact solar cell according to claim 16, characterized in that, The material of the tunneling isolation layer is selected from at least one of the following: silicon oxide, silicon nitride, silicon fluoride, silicon oxyfluoride, silicon carbon oxide, aluminum oxide, aluminum fluoride, and aluminum oxynitride.

20. The back-contact solar cell according to any one of claims 2-4, characterized in that, A second transparent conductive film and / or a second work function adjustment layer are disposed between the second carrier collection terminal and the second electrode; the second transparent conductive film and / or the second work function adjustment layer are both located within the projection area of ​​the second carrier collection terminal; And / or, a first transparent conductive film and / or a first work function adjustment layer are disposed between the first carrier collection terminal and the first electrode; The first transparent conductive film and / or the first work function adjustment layer are both located within the projection area of ​​the first carrier collection end.

21. The back-contact solar cell according to claim 20, characterized in that, The thickness of both the first work function adjustment layer and the second work function adjustment layer is 0.1-5 nm; the work function of both the first work function adjustment layer and the second work function adjustment layer is 1 eV-5.5 eV. The first transparent conductive film is formed by combining or mixing a transparent conductive material and a work function regulating material; and / or, the second transparent conductive film is formed by combining or mixing a transparent conductive material and a work function regulating material.

22. The back-contact solar cell according to claim 20, characterized in that, When a second transparent conductive film is disposed between the second carrier collection terminal and the second electrode, the second electrode is disposed on the back surface of the second transparent conductive film in the form of a grid line; And / or, if the first transparent conductive film is disposed between the first carrier collection terminal and the first electrode, the first electrode is disposed on the back surface of the first transparent conductive film in the form of a grid line.

23. The back-contact solar cell according to claim 20, characterized in that, The materials of the first transparent conductive film and the second transparent conductive film are each independently selected from at least one of the following: zinc oxide, aluminum-doped zinc oxide, tin oxide, indium-doped tin oxide, and indium-gallium-doped tin oxide.

24. The back-contact solar cell according to claim 21, characterized in that, The work function of the material is adjusted to be 1eV-5.5eV.

25. The back-contact solar cell according to claim 20, characterized in that, The first work function adjustment layer and the second work function adjustment layer are each independently selected from at least one of alkali metals, transition metals, alkali metal halides, or transition metal halides.

26. The back-contact solar cell according to claim 20, characterized in that, The first work function adjustment layer and the second work function adjustment layer are each independently selected from at least one of the following: calcium, magnesium, barium, lithium fluoride, potassium fluoride, magnesium fluoride, and barium chloride.

27. The back-contact solar cell according to any one of claims 2-5, characterized in that, The back surface of the silicon substrate is a planar structure or a light-trapping structure; And / or, the light-facing surface of the silicon substrate is a planar structure or a light-trapping structure.

28. The back-contact solar cell according to any one of claims 2-4, characterized in that, The top view of the second carrier collection end is a dotted or line pattern.

29. The back-contact solar cell according to claim 2 or 4, characterized in that, The light-facing surface of the silicon substrate is provided with at least one of the following: a passivation layer, a front field-effect layer, a front anti-reflection thin film layer, a scattering structure layer, and a light-concentrating structure layer. And / or, in the backlight surface of the metal oxometalate layer, a back passivation film is provided in the area other than the second electrode and the first electrode.

30. The back-contact solar cell according to claim 3, characterized in that, The projection of the second region at least partially overlaps with the projection of the second carrier selection layer; The second carrier selection layer is located on the back or light-facing side of the metal oxo compound layer.

31. The back-contact solar cell according to claim 3 or 30, characterized in that, The area of ​​the projection of the second carrier collection terminal onto the back surface of the silicon substrate accounts for 5% to 45% of the total area of ​​the back surface of the silicon substrate. The area of ​​the projection of the second carrier selection layer onto the back surface of the silicon substrate accounts for 5% to 45% of the total area of ​​the back surface of the silicon substrate.

32. The back-contact solar cell according to claim 3 or 30, characterized in that, When the second electrode is correspondingly disposed on the second carrier selection layer, a third transparent conductive film and / or a third work function adjustment layer are disposed between the second carrier selection layer and the second electrode; the third transparent conductive film and / or the third work function adjustment layer are both located within the projection portion of the second carrier selection layer.

33. The back-contact solar cell according to claim 32, characterized in that, The thickness of the third work function adjustment layer is 0.1-2 nm.

34. The back-contact solar cell according to claim 32, characterized in that, When a third transparent conductive film is disposed between the second carrier selection layer and the second electrode, the second electrode is disposed on the back surface of the third transparent conductive film in the form of a grid line.

35. The back-contact solar cell according to claim 3 or 30, characterized in that, The light-facing surface of the silicon substrate is provided with at least one of the following: a passivation layer, a front field-effect layer, a front anti-reflection thin film layer, a scattering structure layer, and a light-concentrating structure layer. And / or, when the second electrode is correspondingly disposed on the second carrier collection terminal, a backlight antireflection film is disposed in the backlight surface of the metal oxidant compound layer, in the portion other than the first electrode, and in the portion other than the second electrode in the second region. And / or, when the second electrode is correspondingly disposed on the second carrier selection layer, a backlight antireflection film is disposed on the portion of the metal oxo compound layer other than the first electrode and the second electrode in the backlight surface of the second carrier selection layer.

36. The back-contact solar cell according to claim 4, characterized in that, The blocking structure is a slotted structure; and / or, the blocking structure is an insulator.

37. The back-contact solar cell according to claim 4 or 36, characterized in that, The thickness of the blocking structure is greater than or equal to the thickness of the metal oxo compound layer; When the thickness of the blocking structure is greater than the thickness of the metal oxometalate layer, the blocking structure protrudes toward the back surface of the metal oxometalate layer.

38. The back-contact solar cell according to claim 4 or 36, characterized in that, A fourth transparent conductive film and / or a fourth work function adjustment layer are disposed between the second carrier transport region and the second electrode; the fourth transparent conductive film and / or the fourth work function adjustment layer are both located within the projection region of the second carrier transport region; And / or, a first transparent conductive film and / or a first work function adjustment layer are disposed between the first carrier collecting end and the first electrode; the first transparent conductive film and / or the first work function adjustment layer are both located within the projection area of ​​the first carrier collecting end.

39. The back-contact solar cell according to claim 38, characterized in that, The thickness of the fourth transparent conductive film is 0.1-2 nm.

40. The back-contact solar cell according to claim 38, characterized in that, When a fourth transparent conductive film is provided between the second carrier transport region and the second electrode, the second electrode is provided on the back surface of the fourth transparent conductive film in the form of a grid line. And / or, if a first transparent conductive film is provided between the first carrier collection terminal and the first electrode, the first electrode is provided in the form of a grid line on the back surface of the first transparent conductive film.

41. The back-contact solar cell according to claim 5, characterized in that, In the metal oxometalate layer, a blocking structure is provided between the second carrier transport region and the first carrier collection end.

42. The back-contact solar cell according to claim 41, characterized in that, The blocking structure is a slotted structure; and / or, the blocking structure is a high-resistivity body, the resistivity of which is more than 100 times that of the metal oxometalate layer.

43. The back-contact solar cell according to claim 5 or 41, characterized in that, The thickness of the second carrier selective collection layer is 1-500 nm.

44. The back-contact solar cell according to claim 5 or 41, characterized in that, The area of ​​the projection of the second carrier selection and collection layer onto the back surface of the silicon substrate accounts for 5% to 45% of the total area of ​​the back surface of the silicon substrate.

45. The back-contact solar cell according to claim 5, characterized in that, It also includes a tunneling isolation layer; the tunneling isolation layer is located between the back surface of the silicon substrate and the light-facing surface shared by the metal oxo compound layer and the second carrier selective collection layer; the thickness of the tunneling isolation layer is 0.1nm-5nm, and the tunneling isolation layer is a single layer or multiple layers.

46. ​​The back-contact solar cell according to claim 5 or 41, characterized in that, A fifth transparent conductive film and / or a fifth work function adjustment layer are disposed between the second electrode and the second carrier selective collection layer; the fifth transparent conductive film and / or the fifth work function adjustment layer are both located within the projection area of ​​the second carrier selective collection layer; And / or, a first transparent conductive film and / or a first work function adjustment layer are disposed between the first electrode and the first carrier collection terminal; The first transparent conductive film and / or the first work function adjustment layer are both located within the projection area of ​​the first carrier collection end.

47. The back-contact solar cell according to claim 46, characterized in that, The thickness of the fifth work function adjustment layer is 0.1-2 nm.

48. The back-contact solar cell according to claim 46, characterized in that, When the fifth transparent conductive film is disposed between the second electrode and the second carrier selective collection layer, the second electrode is disposed on the back surface of the fifth transparent conductive film in the form of a grid line. And / or, if the first transparent conductive film is disposed between the first electrode and the first carrier collection terminal, the first electrode is disposed on the back surface of the first transparent conductive film in the form of a grid line.

49. The back-contact solar cell according to claim 5 or 41, characterized in that, The top view of the second carrier selection collection layer is a dotted or line pattern.

50. The back-contact solar cell according to claim 5, characterized in that, The light-facing surface of the silicon substrate is provided with at least one of the following: a passivation layer, a front field-effect layer, a front anti-reflection thin film layer, a scattering structure layer, and a light-concentrating structure layer. And / or, in the backlight surfaces of both the metal oxo compound layer and the second carrier transport region, a back antireflection film is provided in the area other than the first electrode and the second electrode.

51. A method for producing a back-contact solar cell, characterized in that, include: Provide silicon substrate; The back surface of the silicon substrate is divided into a first region and a second region. A metal oxo compound layer is deposited in at least the first region of the silicon substrate; The metal oxo compound layer and the region corresponding to the first region form a first carrier collection terminal; A first electrode is correspondingly disposed on the first carrier collection terminal; A second electrode is disposed in the area corresponding to the second region.

52. The method for producing a back-contact solar cell according to claim 51, characterized in that, Prior to depositing a metal oxalate layer at least in the first region of the silicon substrate, the method further includes: The silicon substrate in the second region is doped to form a second carrier collection terminal; The step of depositing a metal oxo compound layer at least in the first region of the silicon substrate includes: A metal oxidant compound layer is deposited on the entire back surface of the silicon substrate; the metal oxidant compound layer and the region corresponding to the second region form a second carrier transport region; The step of setting a second electrode in the region corresponding to the second region includes: The second electrode is disposed on the second carrier transport region.

53. A back-contact battery assembly, characterized in that, include: The back-contact solar cell according to any one of claims 1 to 50.