A solar cell, a solar module and a method for manufacturing a solar cell

Abstract

A solar cell includes a silicon substrate and a layered structure disposed on the surface of the silicon substrate. The layered structure includes: a first layer containing a percentage of crystalline material disposed in an amorphous matrix, the first layer being disposed on the surface of the silicon substrate; and a second layer containing a percentage of crystalline material disposed in an amorphous matrix, the second layer being interposed between the first layer and the surface of the silicon substrate; wherein the percentage of crystalline material in the first layer is greater than the percentage of crystalline material in the second layer.

Description

Technical Field

[0001] This disclosure relates to solar cells and methods for their formation. Prior Technology

[0002] A solar module that generates electricity from sunlight contains an array of solar cells / photovoltaic cells, each containing a multilayer semiconductor structure configured between one or more front and back electrodes.

[0003] The substrate typically forms a pn junction with the emitter layer (i.e., one of the substrate and the emitter layer is an n-type material, and the other is a p-type material), which responds to the light incident on the solar cell to facilitate the generation of current.

[0004] Solar cells may also include an accumulation layer disposed on a portion of the substrate opposite to the emitter layer. The accumulation layer forms a highly doped layer configured to draw charge carriers from the substrate. The accumulation layer may be either a front surface field (FSF) or a back surface field (BSF) layer, depending on whether it is disposed on the front or back side of the substrate. For example, if the accumulation layer is disposed on the back side of the substrate (i.e., defining the BSF), the emitter layer is disposed on the front side of the substrate to define the front-side junction solar cell.

[0005] Accordingly, one of the emitter layer and the accumulation layer is electrically connected to the front electrode, and the other of the emitter layer and the accumulation layer is connected to the back electrode. The emitter layer and the accumulation layer are typically formed of amorphous silicon (a-Si), while the substrate is formed of crystalline silicon (c-Si), thus defining heterojunction technology (HJT) solar cells.

[0006] To maximize the efficiency of this type of solar cell, it is crucial to minimize the number of surface defects that can form at the interfaces between different layers in a multilayer structure. This is because surface defects can be detrimental to the operation of the solar cell. For example, charge carriers recombine at defects located near the pn junction, rather than being collected by the electrodes. Charge carrier recombination is a major cause of reduced photovoltaic conversion efficiency in solar cells.

[0007] One way to reduce the negative effects of surface defects is to passivate the interfaces formed in solar cells. Typically, this is achieved by forming an intrinsic (i.e., undoped) semiconductor material layer between the substrate and each of the emitter and accumulation layers. The presence of this intrinsic layer reduces charge carrier recombination on the substrate surface, thereby improving the efficiency of the solar cell.

[0008] While the presence of an intrinsic layer is advantageous, it also leads to the formation of further interfaces within the solar cell (e.g., between the intrinsic layer and the overlying emitter layer). This provides another area for impurity accumulation, thereby increasing charge carrier recombination. If the intrinsic layer is too thick, it can also inhibit charge carrier transport toward the electrodes, increasing the resistivity of the solar cell.

[0009] Incidentally, the interface between intrinsic and doped semiconductor layers can lead to abrupt changes in conductivity and / or band gap. The resulting band bending at the interface can lead to high-density interface states, which is another source of charge carrier recombination.

[0010] Therefore, it is necessary to reduce the prevalent charge carrier recombination in this type of solar cell, and at the same time, it is necessary to improve the charge carrier transport properties. Summary of the Invention

[0011] According to the first aspect, a solar cell is provided, which includes a substrate (such as a silicon substrate) and a layered structure disposed on the surface of the substrate, the layered structure comprising; The first layer comprises a percentage of crystalline material disposed within an amorphous matrix, and the first layer is disposed on the surface of the substrate; The second layer contains a percentage of crystalline material disposed within the amorphous matrix, and the second layer is interposed between the first layer and the substrate surface; The percentage of crystalline material in the first layer is greater than the percentage of crystalline material in the second layer.

[0012] The higher concentration of crystalline material in the first layer reduces the resistivity of the layered structure away from the substrate. This can reduce the contact resistivity between the layered structure and the electrodes of the solar cell, thereby increasing the fill factor of the solar cell. In contrast, the higher concentration of amorphous material in the second layer leads to increased light absorption towards the surface of the substrate, thereby increasing the short-circuit current (Isc) and thus increasing the efficiency of the solar cell.

[0013] The optional features will now be listed. These features can be applied individually or in any combination with any aspect.

[0014] It will be understood that when an element, such as a layer, film, region, or substrate, is referred to as "on," "adjacent to," or "opposite to" another element, it can be "directly on," "directly adjacent to," or "directly opposite" to that further element; alternatively, one or more intermediate elements may be present. Conversely, when an element is referred to as "directly on," "directly adjacent to," or "directly opposite to" another element, no intermediate elements are present.

[0015] The first layer may be directly disposed on the second layer. In this way, the concentration of the crystalline material at the interface between the first and second layers may change in a defined phase. Thus, there may be no substantially amorphous layer disposed between the first and second layers.

[0016] A layered structure may be defined here as having first and second layers; however, it will be appreciated that a layered structure may also contain two or more layers, such as multiple layers, in a particular specific pattern. It is understood that the layers of a layered structure may be discrete layers, with defined stages of change in the percentage of crystalline material between adjacent layers. Thus, it is clear that boundaries may appear between these discrete layers, each boundary defined by stages of change in the percentage of crystalline material.

[0017] The layers may be configured such that at least one or each layer of the layered structure may have a substantially hierarchical structural composition when measured across its depth(s). In this way, the structural composition of at least one or each layer may vary such that the concentration of the crystalline material increases gradually as it moves away from the substrate. The layers may be configured such that the percentage of crystallinity at any depth in the first layer will be greater than the percentage of crystallinity at any depth in the second layer, thus providing a relative change in the percentage of crystallinity across the depths of the layered structure.

[0018] Incidentally, it is important to understand that a layered structure may contain multiple layers, each with a continuously hierarchical structure, such that there are no distinct phases across the layered structure defining the percentage of crystalline material. Thus, it is clear that boundaries (as described above) may not appear between continuously hierarchical layers, and the percentage of crystalline material may instead gradually change across the thickness of the layered structure. Furthermore, it should be understood that in certain specific cases, one or more layers of the layered structure may be discrete layers, and one or more other layers within the same layered structure may be continuously hierarchical layers.

[0019] Crystalline materials are defined as materials that exhibit long-range regularity in at least one direction. Accordingly, such crystalline materials are composed of atoms arranged in a unit cell that repeats over large distances, for example, the constituent atoms exhibit translational periodicity.

[0020] In contrast, amorphous materials are characterized by short-range regularity, where the atoms are bonded in irregular, random spatial positions because factors that do not allow for regular arrangement are not allowed.

[0021] Single-crystal materials are defined as materials composed solely of crystalline materials having a single continuous lattice (e.g., without internal grain boundaries). Accordingly, such single-crystal materials consist only of crystalline materials in which amorphous material is substantially absent. Polycrystalline materials (known as polycrystalline materials) are composed of a plurality of crystals or grains. Each crystal exhibits long-range regularity of atoms within the unit cell defining the crystal structure. Accordingly, such polycrystalline materials (and polycrystalline materials) consist only of crystalline materials in which amorphous material is substantially absent. Both single-crystal and polycrystalline materials exhibit long-range regularity in substantially all directions.

[0022] The substrate may be composed of crystalline silicon (c-Si). A crystalline silicon substrate may contain a continuous crystal structure, such as monocrystalline silicon. Alternatively, the substrate may contain one or more grains of a continuous crystal structure, such as polycrystalline (or polycrystalline) silicon.

[0023] Regarding the first and second layers of the layered structure, the crystalline material in each of these layers is defined as having a quasi-crystalline structure, exhibiting short and / or medium-distance regularity in its crystal structure, but lacking long-distance regularity in at least one direction. Accordingly, each of the first and second layers of the layered structure at least partially contains amorphous material, in which crystalline material is disposed or embedded. This contrasts with single-crystal or polycrystalline materials composed solely of crystalline material.

[0024] The material in each of the first and second layers may be configured to include one or more crystalline regions disposed or embedded in an amorphous matrix. For example, the crystalline material may be or include one or more discrete grains disposed within the matrix of the amorphous material. Each crystalline region may exhibit a degree of long-range regularity in its crystal structure. In view of the above, it will be appreciated that each of the first and second layers (together with the third layer described below) may be configured such that they are not formed of single-crystal and / or polycrystalline (known as polycrystalline) materials.

[0025] The first and second layers may each have a width, length, and depth. Each such layer may be constructed such that its width and length are substantially greater than its depth. The width and length of the layer may be measured in a direction perpendicular to a plane aligned with the substrate surface, and the depth may be measured in a direction perpendicular to a plane perpendicular to the substrate surface. Crystalline material (e.g., multiple crystalline regions) may be evenly distributed across the depths of the layers.

[0026] The crystalline regions or grains may be configured such that they substantially all have a size at the nanometer scale (i.e., substantially all crystalline regions have at least one scale measured to be less than 1000 nanometers). Thus, at least one or each of the first, second, and third layers may be formed of a nanocrystalline material. In an exemplary embodiment, substantially all crystalline regions or grains may be configured such that at least one scale is approximately less than 15 nanometers, alternatively approximately less than 10 nanometers.

[0027] According to the exemplary configuration, virtually all crystalline regions or grains may be constructed such that at least one dimension is approximately less than 5 nanometers. According to a further exemplary configuration, virtually all multiple crystalline regions or grains may be constructed such that the largest dimension is less than 5 nanometers. According to a further exemplary configuration, virtually all crystalline regions or grains may be constructed such that virtually all dimensions are measured to be approximately less than 5 nanometers.

[0028] As described above, the first layer has a higher percentage or concentration of crystalline material than the second layer. The concentration of crystalline material in each layer can be defined as the mass or volume fraction of the individual layer.

[0029] According to an exemplary embodiment, the percentage of crystalline material in the first layer may be between 75% and 100%, alternatively between 70% and 100%. In one embodiment, the percentage of crystalline material in the first layer may be a constant value. In another embodiment, the percentage of crystalline material in the first layer may vary, wherein the percentage crystallinity increases in the direction away from the substrate.

[0030] The percentage of crystalline material in the second layer may be between 50% and 75%, or alternatively between 50% and 70%. In one specific case, the percentage of crystalline material in the second layer may be a constant value. In another specific case, the percentage of crystalline material in the second layer may vary, wherein the percentage of crystallinity increases in the direction away from the substrate.

[0031] In an exemplary specific configuration, the first layer may have a percentage of crystalline material varying between 75% and 100%, and the second layer may have a percentage of crystalline material varying between 50% and 75%, wherein the percentage crystallinity in both the first and second layers increases in the direction of movement away from the substrate. According to this configuration, the percentage crystallinity of the first and second layers is graded across the interfaces between the layers, resulting in a continuous gradation of the crystallinity of the layered structure across its depth.

[0032] The layered structure may include a third layer containing a percentage of crystalline material disposed within the amorphous matrix. The third layer may be interposed between the second layer and the surface of the substrate. The layered structure may further include a passivation layer, which may be interposed between the third layer and the surface of the substrate. In this manner, the third layer may be directly interposed between the second layer and the passivation layer.

[0033] The passivation layer may be formed of an amorphous material, which may be constructed to passivate the surface of a substrate with a layered structure. Depending on the specific example, the passivation layer may be formed solely of an amorphous material.

[0034] The third layer of the layered structure may be constructed in a manner similar to the first and second layers. In this case, the crystalline material in the third layer may be defined as having a quasi-crystalline structure, exhibiting short and / or medium-distance regularity in its crystal structure, but lacking long-distance regularity in at least one direction. The third layer may at least partially comprise amorphous material, within which crystalline material is configured or embedded, such that it does not constitute a single crystal or polycrystalline material. Furthermore, the material in the third layer may be constructed comprising one or more crystalline regions configured or embedded within an amorphous matrix, as described in the preceding paragraphs.

[0035] The percentage of crystalline material in the third layer may be less than or substantially the same as the percentage of crystalline material in the second layer. By constructing a third layer with a smaller percentage of crystalline material, it increases the relative proportion of amorphous material present in that layer, meaning that the thickness of the passivation layer can be reduced while maintaining passivation of the substrate surface. Reducing the thickness of the passivation layer can further reduce the resistivity of the layered structure, thereby increasing the fill factor of the solar cell. The presence of more amorphous material in the third layer also increases photon absorption near the substrate, thereby increasing the efficiency of the solar cell. By providing a third layer with a lower percentage of crystalline material than the second layer, this gradual change in crystallinity (e.g., across the layered structure) reduces the resistivity difference between adjacent layers, which could otherwise restrict the flow of charge carriers (e.g., from the solar cell substrate to the electrodes).

[0036] According to the exemplary configuration, at least one of the first and second layers may have a compositional gradient across its depth(s). The third layer may be compositionally graded across its depth, from substantially amorphous at the interface with the passivation layer to at least partially crystalline at the interface with the second layer. The second layer may be compositionally graded across its depth, from lower crystallinity at the interface with the third layer to higher crystallinity at the interface with the first layer. The first layer may be compositionally graded across its depth, from lower crystallinity at the interface with the second layer to higher crystallinity at the interface with the electrode.

[0037] According to exemplary configurations, a solar cell may include electrodes disposed on a surface of a layered structure opposite to the surface that forms an interface with the substrate (e.g., such that the layered structure may be interposed between the substrate and the electrodes). A transparent conductive oxide (TCO) may be interposed between the electrodes and the layered structure, positioning it to directly contact the first layer. The TCO and the electrodes may each be configured to draw charge carriers from the layered structure (especially the first layer). In this case, by constructing a first layer with a higher concentration of crystalline material, it generates better electrical (e.g., ohmic) contact with the TCO layer to increase charge carrier absorption from the layered structure, thereby increasing the fill factor of the solar cell.

[0038] Each layer of the layered structure may be formed of a material having a defined chemical composition. Each layer may be deposited (or, for example, diffused or implanted) onto a substrate. The amorphous matrix material may be formed of the same material, such as a material having the same chemical composition as the crystalline material regions(s). Alternatively, the crystalline material regions(s) may be formed of a material different from the amorphous matrix material.

[0039] The first layer may be formed of a first material, comprising at least one of silicon, silicon suboxide (SiOx), and silicon carbide (SiC). The second layer may be formed of a second material, comprising at least one of silicon, silicon suboxide (SiOx), and silicon carbide (SiC). The third layer may be formed of a third material, comprising at least one of silicon, silicon suboxide (SiOx), and silicon carbide (SiC). In each of the above layers, silicon, silicon suboxide (SiOx), and silicon carbide (SiC) may appear in amorphous and crystalline forms.

[0040] The concept of secondary silicon oxide will be defined as a class of silicon oxides in which the electronegative element (i.e., silicon) is present in excess compared to normal oxides (such as SiO₂). Secondary silicon oxide can be deposited by vapor deposition at relatively low temperatures (e.g., below 300°C), which avoids any damage to the underlying amorphous silicon.

[0041] Compared to an equivalent layer formed purely of silicon, the use of silicon suboxide and / or silicon carbide increases the conductivity and transparency of the layer.

[0042] The passivation layer may be formed of amorphous silicon (a-Si). Alternatively, the passivation layer may be formed of at least one of amorphous silicon suboxide (SiOx) and amorphous silicon carbide (SiC).

[0043] According to exemplary configurations, the layered structure may be configured on the surface of the substrate where light from a radiation source (such as the sun) is incident during use (e.g., the front side of the substrate, which is configured to face the radiation source when the solar cell is in use). In this case, each of the first, second, third, and passivation layers may be formed of at least one of silicon suboxide (SiOx) and silicon carbide (SiC). Note that the back side of the substrate should be understood as opposite to the front side of the substrate, and that during use, incident light hits the front surface before hitting the back surface.

[0044] Compared to an equivalent structure formed from silicon, the inclusion of silicon dioxide and / or silicon carbide contributes to increased transparency of the layered structure. The difference in absorbance can be attributed to the different band gaps of these materials. Furthermore, by reducing light absorption in the first layer, SiOx / SiC also increases the short-circuit current (Isc) and thus the efficiency of the solar cell. This effect is at least partly due to the increased number of photons that can pass through the layered structure on the front side of the substrate without being absorbed. These unabsorbed photons are more likely to reach the substrate, where they can contribute to the number of photocharge carriers generated by the solar cell.

[0045] According to exemplary configurations, layered structures are arranged on surfaces of the substrate where light does not directly strike (e.g., the back side of the substrate). In this case, the inclusion of secondary silicon oxide and / or silicon carbide in the first layer may be particularly advantageous because it increases the conductivity of the layer compared to an equivalent layer formed of amorphous silicon.

[0046] The silicon dioxide and / or silicon carbide materials in the first and second layers enhance the charge carrier transport properties between the layered structure and the corresponding electrodes of the solar cell. In particular, the silicon dioxide and / or silicon carbide cause the energy band to bend at the interface between the first layer and the electrodes to increase charge carrier tunneling therebetween.

[0047] The third layer may be formed of silicon (Si). Silicon can exist in both amorphous and crystalline forms. The passivation layer may be formed of amorphous silicon. Compared to silicon suboxide and / or silicon carbide, silicon in the third layer increases the passivation of the substrate. Silicon can also advantageously increase photon absorption near the substrate, which increases the number of photogenerated charge carriers produced by the solar cell.

[0048] As we have learned from the preceding text, both substrates and layered structures can be formed from one or more semiconductor materials. Each semiconductor material may be configured with a type of conductivity, which is determined by the doping atoms it contains. In this way, each individual semiconductor material may be doped with atoms having a predetermined charge to increase the excess charge carriers in the overall doped material.

[0049] Accordingly, at least one layer of the layered structure may be constructed with a conductivity type determined by the number of doped atoms it contains. The first layer may contain a first concentration of doped atoms. The second layer may contain a second concentration of doped atoms, which is less than the first concentration of doped atoms in the first layer. The third layer may contain a third concentration of doped atoms, which is less than the second concentration of doped atoms in the second layer.

[0050] When measured across depth, the layered structure may be constructed to contain two or more stages of dopant concentration variation. The first dopant concentration variation occurs between the third and second layers, while a second dopant concentration variation occurs at the interface between the second and third layers. The relatively low dopant concentration in the third layer contributes to increased passivation of the substrate surface, while the sequential and gradual change in dopant concentration results in a gradual decrease in resistivity across the layered structure, thereby increasing the fill factor of the solar cell.

[0051] In an exemplary configuration, the first layer may be electrically connected to the electrodes of the solar cell. The higher doping concentration in the first layer (relative to the second and third layers) leads to increased charge carrier transport within and / or through the first layer. This, in turn, improves the electrical connection between the layered structure and the electrodes.

[0052] In specific cases, layered structures may contain multiple layers, and their construction is such that when measured across their depth, the layered structure contains a substantially hierarchical structural composition. In this example, the dopant concentration of the layered structure may gradually increase as it moves away from the substrate.

[0053] It will be understood that the ionization state of the doped atoms can determine the conductivity type of the doped semiconductor material. For example, a semiconductor material may be positively or negatively doped to exhibit a positive conductivity type (p-type) or a negative conductivity type (n-type), respectively. Either layer with a determined conductivity type (e.g., p-type or n-type) may form an electrostatic driving force that drives photogenerated charge carriers (e.g., electrons and holes) toward that layer. For example, p-type materials will attract electrons and repel holes, while n-type materials will attract holes and repel electrons. In some cases, the semiconductor material may be undoped (e.g., with an inherent passivation layer).

[0054] The substrate may be constructed with a first conductivity type (e.g., n-type), and the layered structure may be constructed with a second conductivity type opposite to the first conductivity type (e.g., p-type), thus forming a pn junction together with the substrate. According to this configuration, the layered structure may define the emitter of the solar cell.

[0055] The interface formed between the p-type and n-type materials at the pn junction allows excess electrons and holes to diffuse into the n-type and p-type materials, respectively. This relative movement of charge carriers results in the formation of a depletion region (e.g., a space charge region) at the pn junction. Once thermal equilibrium is reached, a built-in potential difference is formed across the depletion region.

[0056] During the operation of a solar cell, the multiple electron-hole pairs generated by light incident on the substrate are separated into electrons and holes by an electric field generated from the built-in potential difference at the pn junction. The separated electrons then move (e.g., tunnel) into the n-type semiconductor, and the separated holes move into the p-type semiconductor. Therefore, when the substrate is n-type and the emitter is p-type, the separated holes and electrons move to the emitter and substrate, respectively. Accordingly, electrons become the dominant carriers in the substrate, and holes become the dominant carriers in the emitter.

[0057] Based on exemplary configurations, the substrate may be formed from n-type monocrystalline silicon wafers, which exhibit a longer lifetime compared to p-type monocrystalline silicon wafers. At least one layer of the layered structure may contain a non-monocrystalline material (e.g., amorphous or nanocrystalline), which is at least partially doped to be p-type. This configuration may facilitate the formation of heterojunction technology (HJT) type solar cells, so defined because it combines two different materials to generate a charge separation field at the pn junction. The passivation layer may be constructed to be of a non-conductive type, thus forming the essential layer between the emitter and the substrate.

[0058] When a semiconductor material is n-type, it may contain impurities containing group V elements, such as phosphorus (P), arsenic (As), and antimony (Sb). When a semiconductor material is p-type, it may contain impurities containing group III elements, such as boron (B), gallium (Ga), and indium (In).

[0059] Alternatively, the emitter may be n-type and the substrate may be p-type, thus forming a pn junction therebetween. In this example, during the operation of the solar cell module, separate holes and electrons move to the substrate and emitter, respectively.

[0060] Depending on the exemplary configuration of the alternative options, the layered structure may be constructed with a first conductivity type (e.g., n-type), identical to the substrate. Thus, the layered structure may define the accumulator of the solar cell, configured to selectively pick up or draw charge carriers from the substrate. In a specific case, the substrate may be formed from n-type monocrystalline silicon wafers, and each layer of the layered structure may contain a non-monocrystalline material, at least partially doped to be n-type. The passivation layer may be constructed with a non-conductivity type, forming the essential layer between the accumulator and the substrate.

[0061] Just as a layered structure has a defined conductivity type, at least one or each layer may also have different dopant concentrations. The first layer may have a first concentration of doped atoms, which is greater than that of the second and / or third layers. The second layer may have a second concentration of doped atoms, which is less than that of the first layer but greater than that of the third layer. The third layer may have a third concentration of doped atoms, which is less than that of the first and / or second concentrations. In this way, the first layer defines a heavily doped layer (p++, n++) of the layered structure, the second layer defines a moderately doped layer (p+, n+) of the layered structure, and the third layer defines a lightly doped layer (p, n) of the layered structure.

[0062] As described above, each doped layer may be configured to generate electrostatic driving forces that drive photogenerated charge carriers (such as electrons and holes) toward the individual layer. Heavily doped layers generate stronger electrostatic forces, leading to increased charge transport and movement away from the substrate. For example, compared to second and third layers formed from moderately and lightly doped p-type materials (i.e., p+ and p), the first layer formed from heavily doped p-type materials (i.e., p++) may exert a greater attractive force on photogenerated charge carriers in the solar cell.

[0063] The doping concentration of at least one or each of the first, second, and third layers may be as high as 10%, optionally as high as 5%, optionally as high as 2%, and optionally as high as 1%.

[0064] In specific configurations, the first and second layers may have a combined depth of less than 9 nanometers. The combined depth of the first and second layers may be at least 1 nanometer. The depth of the first layer may be 2 nanometers. The depth of the second layer may be 7 nanometers. The third layer may have a depth of less than 5 nanometers. The depth of the third layer may be less than 4 nanometers. The depth of the third layer may be at least 1 nanometer. The depth of the third layer may be 2 nanometers.

[0065] According to an exemplary embodiment, the layered structure includes first, second, and third layers, each containing a progressively lower percentage of crystalline material disposed within an amorphous matrix. It will be appreciated that the layered structure may include one or more additional layers, such as fourth, fifth, and / or sixth layers, interposed between the third layer and the substrate, each having a progressively lower or substantially equal percentage of crystalline material. Furthermore, each additional layer may have a progressively lower or equal dopant concentration.

[0066] When a solar cell is in use, the surface of the substrate may define the surface on which light from a radiation source first strikes (i.e., the light strikes this surface before hitting the opposite surface of the substrate). Thus, this surface may define the front side (i.e., the frontmost side) of the substrate. Alternatively, this surface may be configured such that when the solar cell is in use, it is not directly exposed to incident light from the radiation source (i.e., the light strikes this surface after hitting the opposite surface of the substrate). Accordingly, this surface may define the back side (i.e., the rearmost side) of the substrate. The solar cell may be configured such that the front side is exposed to incident light and the back side is exposed to reflected light.

[0067] According to an exemplary configuration, the layered structure may define a front layered structure disposed on the front side of the substrate, such that the first and second layers respectively define the first and second front layers. The solar cell may further include a back layered structure disposed on the back side of the substrate opposite to the front side.

[0068] The back-side layered structure may include first and second back-side layers, each containing a percentage of crystalline material disposed within an amorphous matrix. A second back-side layer may be interposed between the first back-side layer and the back side of the substrate. The percentage of crystalline material in the first back-side layer may be greater than the percentage of crystalline material in the second back-side layer.

[0069] The back-side layered structure may be constructed in the same manner as the front-side layered structure, as defined in any of the preceding paragraphs. For example, each layer of the back-side layered structure may be formed of a material having a defined chemical composition. Each of the first and / or second back-side layers may be deposited (or, for example, diffused or implanted) onto the substrate. The first and / or second back-side layers may be at least partially or substantially formed of at least one of silicon suboxide and silicon carbide.

[0070] The back-side layered structure may include a third back-side layer and a passivation layer. The third back-side layer may be interposed between the back side of the substrate and the first and second back-side layers. The passivation layer may be interposed between the third back-side layer and the back side of the substrate.

[0071] The back passivation layer may be formed of amorphous silicon (a-Si), which may constitute the back side of the passivation substrate. The third layer may be formed at least partially or substantially of a concentration of crystalline material disposed within the amorphous matrix. The percentage of crystalline material in the third back layer may be less than the percentage of crystalline material in the second and / or first layers. The third back layer may be formed of silicon.

[0072] According to an exemplary specific configuration, each layer in the frontal layered structure may be formed of at least one of silicon suboxide (SiOx) and silicon carbide (SiC). Each layer contains crystalline regions of silicon suboxide (SiOx) and / or silicon carbide (SiC) disposed in an amorphous matrix of silicon suboxide (SiOx) and / or silicon carbide (SiC), and the frontal passivation layer is formed of amorphous silicon suboxide (SiOx) and / or silicon carbide (SiC).

[0073] The back-side layered structure is reversed. The first and second back-side layers may be formed of crystalline regions of silicon suboxide (SiOx) and / or silicon carbide (SiC), which are disposed within an amorphous matrix of silicon suboxide (SiOx) and / or silicon carbide (SiC). The third back-side layer and the passivation layer may each be formed of silicon. The third back-side layer may contain crystalline regions of silicon disposed within an amorphous silicon matrix, and the back-side passivation layer may be substantially composed of amorphous silicon.

[0074] Each layer of the front-side layered structure may be configured with either positive or negative conductivity (p-type or n-type). Each layer of the back-side layered structure may be configured with either positive or negative conductivity (n-type or p-type). In a typical configuration, the layers of the front-side layered structure may be configured with negative conductivity (n-type). The layers of the back-side layered structure may be configured with positive conductivity (p-type). The substrate may be configured with negative conductivity (n-type).

[0075] The first back layer may have a higher concentration of doped atoms than the second and / or third back layers. The second back layer may have a lower concentration of doped atoms than the first back layer but higher than the third back layer.

[0076] The third back layer may be constructed with a dopant concentration lower than that of either the first or second back layer. In this way, the first back layer defines a heavily doped layer of the back layered structure, the second back layer defines a moderately doped layer of the back layered structure, and the third back layer defines a lightly doped layer of the back layered structure.

[0077] In a specific case, the front(s) of the substrate may be textured to form textured surfaces, which correspond to uneven surfaces or have uneven features. In this example, the amount of light incident on the substrate is increased due to the textured surface of the substrate, which may improve the efficiency of the solar cell.

[0078] The layered structure may further include an anti-reflective layer or cladding configured opposite to the first layer. The anti-reflective layer may be configured such that at least the first layer is interposed between the anti-reflective layer and the substrate. The anti-reflective layer may have a single-layer or multi-layer structure. The anti-reflective layer may be formed of a transparent conductive oxide (TCO), such as indium tin oxide (ITO), or of a transition metal oxide (TMO), which has been textured to provide an anti-reflective surface. The anti-reflective layer advantageously reduces the reflectivity of light incident on the solar cell and increases the selectivity of a predetermined wavelength band, thereby increasing the efficiency of the solar cell.

[0079] The anti-reflective layer may be configured such that at least a first layer is interposed between the transparent conductive oxide cladding and the substrate. The transparent conductive oxide cladding may be electrically connected to the first layer. The transparent conductive oxide cladding may be configured to increase lateral carrier transport to electrodes disposed on individual surfaces of the layered structure.

[0080] As described above, a solar cell may include electrodes configured opposite to a layered structure and constructed to draw photogenerated charge carriers from the solar cell. The electrodes may be configured such that the layered structure is interposed between the electrodes and the substrate.

[0081] When the layered structure is disposed on the back side (e.g., the very back side) of the substrate, the electrodes may be disposed on the back side of the layered structure to define the back electrode of the solar cell.

[0082] When the layered structure is disposed on the front side (e.g., the frontmost side) of the substrate, the electrodes may be disposed on the front side of the layered structure to define the front electrode of the solar cell.

[0083] When a solar cell comprises a front layered structure and a back layered structure respectively disposed on the front and back sides of a substrate, the solar cell may include a front electrode disposed on the front side of the front layered structure and a back electrode disposed on the back side of the back layered structure. Each electrode may be configured to form an ohmic contact with an individual surface of the front and back layered structures.

[0084] The front and back electrodes may each comprise a plurality of finger electrodes disposed on individual surfaces of the layered structure. Each finger electrode may have an axial length substantially greater than its width. Both the width and axial length of the finger electrode may be measured perpendicular to the plane of the individual surface of the layered structure. The finger electrode may extend laterally parallel to the width direction of the layered structure.

[0085] Each of the plurality of front and / or back finger electrodes may be spaced apart across individual surfaces to define a laterally extending space between the finger electrodes. The finger electrodes may be spaced apart longitudinally, substantially parallel to the length direction of the layered structure. Each of the plurality of finger electrodes may be substantially parallel to each other. Accordingly, the plurality of back finger electrodes may form an array of parallel, longitudinally spaced (e.g., equally spaced) finger electrodes.

[0086] It will be understood that terms such as “conductive” and “insulating” as used herein are explicitly intended to mean electrically conductive and electrically insulating, respectively. The meaning of these terms will be particularly evident given the technical context of this disclosure (photovoltaic solar cell devices). It will also be understood that the term “ohmic contact” is intended to mean a non-rectified electrical junction (i.e., a junction between two conductors exhibiting substantially linear current-voltage [IV] characteristics).

[0087] According to an exemplary configuration, a solar cell may include a substrate, a front layered structure disposed on the front side of the substrate, and a back layered structure disposed on the back side of the substrate. The front layered structure may define the front field (FSF) or accumulator of the solar cell, configured to draw charge carriers from the substrate during operation of the solar cell. The accumulator may be electrically connected to the front electrode and configured such that the accumulator is disposed between the front electrode and the substrate. The back layered structure may define an emitter, which is positioned opposite the substrate to form a pn junction.

[0088] According to an exemplary configuration of alternative options, a solar cell may include a substrate, a front layered structure disposed on the front side of the substrate, and a back layered structure disposed on the back side of the substrate. The front layered structure may define an emitter for the solar cell, positioned opposite the substrate to form a pn junction. The emitter may be electrically connected to the front electrode and configured such that the emitter is positioned between the front electrode and the substrate. The back layered structure may define a back field, positioned facing the back side of the substrate, i.e., between the substrate layer and the back electrode. Accordingly, the back field may be configured to draw charge carriers from the substrate and transfer them to the back electrode during operation of the solar cell.

[0089] The second aspect provides a solar module comprising a plurality of solar cells according to the first aspect. The plurality of solar cells may be electrically coupled together.

[0090] According to the third aspect, a method for manufacturing a solar cell according to the first aspect is provided, the method comprising providing a substrate (e.g., a silicon substrate) and disposing a layered structure on the surface of the substrate; the step of disposing the layered structure (e.g., on the silicon substrate) comprises disposing a first layer on the surface of the substrate, and prior to disposing the first layer, disposing a second layer between the first layer and the surface of the substrate such that it is interposed therebetween, the first and second layers each comprising a percentage of crystalline material disposed in an amorphous matrix; wherein the method comprises a percentage of crystalline material in the first layer being greater than the percentage of crystalline material in the second layer.

[0091] Before configuring the first and second layers, the method may include configuring a passivation layer and a third layer on the surface of a substrate. The third layer may contain a percentage of crystalline material configured in an amorphous matrix, and the passivation layer may be formed of an amorphous material.

[0092] Before configuring the third layer, the method may involve configuring a passivation layer between the surface of the third layer and the substrate such that it is interposed therebetween.

[0093] The method may further include a percentage of crystalline material in the third layer that is less than the percentage of crystalline material in the second layer.

[0094] The steps of configuring a layered structure may involve using a vapor deposition process to sequentially deposit layers onto the surface of a substrate. The vapor deposition process may be a plasma-enhanced chemical vapor deposition (PECVD) process. Advantageously, each layer of the layered structure may be deposited using the same deposition method as part of a single, continuous process.

[0095] The method may include controlling at least one parameter of the vapor deposition process to determine the structural, chemical, and dopant composition of at least one layer of the layered structure. The vapor deposition process parameter may include gas composition and / or gas flow rate. The vapor deposition process parameter may define the temperature of the deposition chamber. The gas composition may include at least one of carbon dioxide (CO2), silicon-containing gases (e.g., silane SiH4), and hydrogen (H2).

[0096] The method may involve constructing the structural composition of the layers of a layered structure to determine the concentration of crystalline and / or amorphous materials in each layer. The method may involve constructing the structural composition to determine the size of the crystalline regions in at least one layer. The method may involve controlling at least one of the following to determine the concentration of crystalline materials in the layers of the layered structure: CO2 gas flow rate, silicon-containing gas (e.g., SiH4) flow rate, H2 gas flow rate, plasma power level, plasma temperature, and temperature and / or pressure of the deposition chamber.

[0097] The method may include controlling at least one parameter of the vapor deposition process to determine the chemical composition of at least one layer of the layered structure. The method may include constructing the chemical composition of the first layer using a first material comprising at least one of silicon, silicon suboxide (SiOx), and silicon carbide (SiC). The method may include constructing the chemical composition of the second layer using a second material comprising at least one of silicon, silicon suboxide (SiOx), and silicon carbide (SiC). The method may include constructing the chemical composition of the third layer using a third material comprising at least one of silicon, silicon suboxide (SiOx), and silicon carbide (SiC). It will be appreciated that the aforementioned deposition parameters (e.g., CO2 gas flow rate, silicon-containing gas flow rate, H2 gas flow rate, plasma power level, plasma temperature, temperature and / or pressure of the deposition chamber) may also be controlled to determine the chemical composition of each layer in the layered structure.

[0098] The method may include pretreating the surface of at least one layer of the layered structure to be deposited. The surface pretreating method may include etching the surface with hydrogen (H₂), for example, to etch away silicon oxide from an exposed surface. The method may further include treating the surface with carbon dioxide (CO₂).

[0099] The method may further include post-annealing at least one layer of the layered structure before sequentially depositing the next layer. The post-annealing step may be performed when the layered structure is configured in the same deposition chamber used for depositing the layers.

[0100] The method may include controlling at least one parameter of the vapor deposition process to determine the conductivity type of at least one of the intrinsic, third, second, and first layers. The method may include constructing layers with conductivity types of p-type or n-type. The method may include constructing at least one layer that is substantially undoped (i.e., intrinsic). Doping of the layers may be achieved by controlling the flow rate of a dopant gas entering the deposition chamber. The dopant gas may include: boron-containing gases, such as diborane (B₂H₆) or trimethylboron (B(CH₃)₃) for p-type doping; and phosphorus-containing gases, such as phosphine (PH₃) for n-type doping. The flow rate of the dopant gas may be controlled relative to the flow rate of the silicon-based gas being introduced into the deposition chamber.

[0101] The method may include controlling at least one parameter of the vapor deposition process to determine the dopant concentration of at least one layer of the layered structure. The method may include doping a first layer with a first dopant concentration, doping a second layer with a second dopant concentration, and doping a third layer with a third dopant concentration. The method for determining the first, second, and third dopant concentrations may include controlling the flow rate of dopant gas into the deposition chamber, as described above.

[0102] The method may further include configuring electrodes on a first layer of the layered structure. The layered structure may include a back side (e.g., the rearmost side) and a front side opposite the back side (e.g., the frontmost side). Accordingly, when the layered structure is configured on the back side of the substrate, the method may include configuring electrodes on the back side of the layered structure to define a back electrode. When the layered structure is configured on the front side of the substrate, the method may include configuring electrodes on the front side of the layered structure to define a front electrode.

[0103] The electrode may comprise a plurality of finger electrodes, and the method may involve depositing the plurality of finger electrodes onto the first layer. The method may also involve depositing a conductive material onto the front or back side of the layered structure.

[0104] Conductive materials can be deposited using various methods, including vapor deposition, plating, printing, etc. For example, conductive materials may include printable materials. Methods for depositing conductive materials may involve printing a printable precursor of the printable material onto the surface of a layered structure. The method may further involve curing the printable precursor according to a firing process to form finger electrodes.

[0105] The method may involve configuring at least an anti-reflective layer (or coating) and / or a transparent conductive oxide layer (or coating) between a first layer and an electrode. The method may involve depositing an anti-reflective and / or transparent conductive oxide coating onto the first layer of the layered surface prior to depositing the electrode. The method for depositing the anti-reflective and / or transparent conductive oxide coating may include magnetron sputtering or any other suitable deposition method.

[0106] Those skilled in the art will appreciate that, aside from mutually exclusive cases, features or parameters relating to any of the foregoing aspects may apply to any other aspect. Furthermore, aside from mutually exclusive cases, any feature or parameter described herein may apply to any aspect and / or may be combined with any other feature or parameter described herein. Simple Explanation of the Diagram

[0107] The specific patterns will now be described by referring to the diagrams and using only examples, where: [Figure 1] is a schematic diagram illustrating the layers of a solar cell; and [Figure 2] is a flowchart demonstrating the method for forming the solar cell of Figure 1. Implementation

[0108] The aspects and specific details of this disclosure will now be discussed with reference to the accompanying diagrams. Those skilled in the art will understand the further aspects and specific details.

[0109] Figure 1 schematically illustrates a solar cell 10, which in particular includes a semiconductor substrate 12 comprising: a first surface (i.e., the front side) 14 on which light from a radiation source (such as the sun) is incident during normal use; and a second surface (i.e., the back side) 16 opposite to the front side 14. That is, the front side 14 may be configured to face the sun during use, while the back side 16 may be configured to face away from the sun during use. In this embodiment, the substrate 12 is a crystalline silicon substrate. However, it is understood that in some alternative embodiments, the substrate 12 may be formed of a semiconductor material that is not silicon.

[0110] The substrate 12 divides the solar cell 10 into a front portion 18 facing the front of the substrate 12 and a back portion 20 facing the back of the substrate 12. Light incident on the solar cell 10 passes through the front portion 18, the substrate 12, and then the back portion 20.

[0111] The solar cell 10 is a back-emitter solar cell (especially a back-emitter heterojunction solar cell 10). Thus, the solar cell 10 has a front field 50 or accumulator 50 and an emitter 52 disposed on either side of the substrate 12. Accordingly, the accumulator 50 forms the front portion 18, and the emitter 52 forms the back portion 20. According to the specific embodiment, the substrate 12 is an n-type monocrystalline silicon wafer, which forms a pn junction with the p-type back emitter 52.

[0112] Each of the front and back portions 18, 20 comprises a plurality of layers configured to define separate layered structures. The front portion 18 (also referred to herein as the front layered structure 18) is configured opposite to the front side 14 of the substrate 12, and the back portion 20 (also referred to herein as the back layered structure 20) is configured opposite to the back side 16 of the substrate 12. The constituent layers of the front and back layered structures 18, 20 are sequentially deposited (or, for example, diffused or implanted) onto the respective front and back sides 14, 16 of the substrate 12.

[0113] Each of the front and back portions 18 and 20 is constructed with width, length, and depth. The width and length of each layer are measured in a direction perpendicular to the front and back portions 14 and 16 of the substrate 12. For each layer, its width and length are substantially greater than its depth, which is measured in a direction perpendicular to the front and back portions 14 and 16 of the substrate 12.

[0114] The solar cell 10 further includes a front electrode 30 disposed on the front side 32 of the accumulator 50. A transparent conductive oxide (TCO) layer (not shown, also referred to as front TCO) is also disposed on the front side 32 and sandwiched therebetween. A back electrode 42 is disposed on the back side 44 of the emitter 52, and a further TCO layer (not shown, also referred to as back TCO) is disposed on the back side 44 and inserted between the back electrode 42 and the emitter 52. The front and back TCOs are formed of indium tin oxide (ITO), and the front and back electrodes 30 and 42 are formed of silver.

[0115] The front portion 18 of the solar cell 10, viewed in the order of movement toward the substrate 12, includes a first front layer 22, a second front layer 24, a third front layer 26, and a front passivation layer 28. The first, second, and third front layers 22, 24, and 26 are all n-type, and together they define the accumulator 50 of the solar cell 10.

[0116] The first, second, and third front-side layers 22, 24, and 26 have depths of 3 nm, 7 nm, and 2 nm, respectively (measured in the vertical direction as shown in Figure 1). A passivation layer 28 is interposed between the accumulator 50 and the front-side layer 14 of the substrate 12. It has a depth of 3 nm (measured in the vertical direction as shown in Figure 1).

[0117] The first, second, and third frontal layers 22, 24, and 26 all have different structural compositions. Each contains a region of crystalline material disposed within an amorphous matrix (i.e., defining the crystalline material). However, the first layer 22 has a higher percentage of crystalline material than the second and third layers 24 and 26. The second layer 24 has a higher percentage of crystalline material than the third layer 26 but less than the first layer 22. The third layer 26 has a lower percentage of crystalline material than both the first and second layers 22 and 24. The frontal passivation layer 28 is formed of amorphous material.

[0118] Each of the first, second, and third frontal layers 22, 24, and 26 is formed of nanocrystalline silicon suboxide (nc-SiOx). The passivation layer 28 is formed of amorphous silicon suboxide (a-SiOx).

[0119] As described above, each of the first, second, and third layers 22, 24, and 26 is constructed such that it has an n-type conductivity, which is determined by the number of doped atoms contained in each individual material. However, each layer is constructed with a different dopant concentration. The first front layer 22 has a higher dopant concentration than the second and third layers. The second front layer 24 has a lower dopant concentration than the first front layer but a higher dopant concentration than the third front layer. Finally, the third front layer 26 has a lower dopant concentration than both the first and second layers 22 and 24. In this way, the first front layer 22 defines a heavily doped accumulation layer (n++) of the solar cell 10, the second front layer 24 defines a moderately doped accumulation layer (n+) of the solar cell 10, and the third front layer 26 defines a lightly doped accumulation layer (n) of the solar cell 10.

[0120] The doping concentration gradually increases from the third front layer 26 to the first front layer 22, which enhances the passivation of the front side 14 of the substrate 12 made of the lightly doped third front layer 26. The high doping concentration in the first front layer 22 also ensures good ohmic contact between the accumulator 50 and the front electrode 30.

[0121] The back surface portion 20 of the solar cell 10, viewed in the order of movement toward the substrate 12, includes first, second, and third back surface layers 34, 36, and 38, which together define the emitter 52 of the solar cell 10. The back surface passivation layer 40 of the solar cell 10 is interposed between the emitter 52 and the back surface 16 of the substrate 12.

[0122] Similar to the front passivation layer 28, the back passivation layer 40 has a depth of 3 nanometers, and the first, second, and third back layers 34, 36, and 38 have depths of 3 nanometers, 7 nanometers, and 2 nanometers, respectively.

[0123] Similar to the front layered structure 18, the first, second, and third back layers 34, 36, and 38 each contain regions of crystalline material disposed within the amorphous matrix (i.e., defining the crystalline material). Likewise, the first layer 34 has a higher percentage of crystalline material than the second and third layers 36 and 38. The second layer 36 has a higher percentage of crystalline material than the third layer 38 but less than the first layer 34. The third layer 38 has a lower percentage of crystalline material than both the first and second layers 34 and 36. The back passivation layer 40 is formed of amorphous material.

[0124] The first and second back layers 34 and 36 are formed of nanocrystalline silicon suboxide (nc-SiOx). However, in contrast to the front layered structure 18, the third back layer and the back passivation layer 40 are each formed of substantially pure silicon (Si).

[0125] Each of the first, second, and third back layers 34, 36, and 38 is constructed such that it has p-type conductivity, which is determined by the number of doped atoms contained in each individual material. However, each layer is constructed with a different dopant concentration. The first layer 34 has a higher dopant concentration than the second and third layers. The second layer 36 has a lower dopant concentration than the first layer 34 but a higher dopant concentration than the third layer 38. Finally, the third layer 38 has a lower dopant concentration than both the first and second layers 34 and 36. In this way, the first back layer 34 defines a heavily doped emitter layer (p++) of the solar cell 10, the second back layer 36 defines a moderately doped emitter layer (p+) of the solar cell 10, and the third back layer 38 defines a lightly doped emitter layer (p) of the solar cell 10.

[0126] Figure 2 shows a method 100 for forming a solar cell, such as described above. The method includes a first step 102: providing a crystalline silicon wafer to define a substrate 12 of the solar cell 10. In a second step 104, the method includes depositing front and back passivation layers 28 and 40 onto the front and back sides 14 and 16 of the substrate 12, respectively. In a third step 106, the method includes depositing third layers 26 and 38 onto the front and back passivation layers 28 and 40, respectively. In a fourth step 108, the method includes depositing second layers 24 and 36 onto the front and back sides, respectively, onto the third layers 26 and 38. In a fifth step 110, the method includes depositing first layers 22 and 34 onto the front and back sides, respectively, onto the second layers 24 and 36.

[0127] Steps 104, 106, 108, and 110 of the second to fifth methods involve configuring (or forming) layers on the front and back sides 14 and 16 of the silicon wafer substrate 12. This may include, for example, deposition, diffusion, doping, and / or implantation steps. The layers form the front and back portions 18 and 20 of the aforementioned solar cell 10 (e.g., emitter layer, accumulation layer, passivation layer, etc.).

[0128] In particular, steps three through five, 106, 108, and 110, involve forming doped semiconductor layers for the accumulators and emitters 50 and 52, as defined above. Each of these steps involves depositing and doping the corresponding semiconductor material using a vapor deposition process (e.g., PECVD). Generally, the parameters of the vapor deposition process determine the composition (e.g., structural and / or chemical) of each layer and also the dopant concentration.

[0129] The sixth method step 112 includes depositing front and back TCO layers onto the front and back sides 32, 44 of the accumulator 50 and the emitter 52, respectively. Finally, the seventh method step 114 includes configuring the front and back electrodes 30, 42 on the outermost surfaces of the front and back portions 18, 20 of the solar cell 10.

[0130] The steps for forming the front and back layers are not limited to those described above. For example, at least one or each front layer may be deposited before or after at least one or each back layer, depending on the design of the vapor deposition apparatus.

[0131] It will be understood that the invention is not limited to the specific embodiments described above, and various modifications and improvements can be made without departing from the concept described herein. Except in cases of mutual exclusion, any feature may be used separately or in combination with any other feature, and this disclosure extends to and includes all combinations and sub-combinations of one or more features described herein.

[0132] 10: Solar cells 12: Semiconductor substrate 14: Front 16: Back 18: Front view, front layered structure 20: Back side, back layered structure 22: First front layer 24: Second front layer 26: Third front layer 28: Front passivation layer 30: Front electrode 32: Front 34: First back layer 36: Second back layer 38: Third back layer 40: Backside passivation layer 42: Back electrode 44: Back 50: Accumulator 52: Launcher 100: Methods for forming solar cells 102~114: Methods and steps for forming solar cells

Claims

1. A solar cell comprising a silicon substrate and a layered structure disposed on the surface of the silicon substrate, the layered structure comprising: a first layer comprising a percentage of crystalline material disposed in an amorphous matrix, the first layer being disposed on the surface of the silicon substrate; a second layer comprising a percentage of crystalline material disposed in an amorphous matrix, the second layer being interposed between the first layer and the surface of the silicon substrate; wherein the percentage of the crystalline material in the first layer is greater than the percentage of the crystalline material in the second layer; and wherein the percentage of the crystalline material in the second layer is greater than zero.

2. The solar cell according to claim 1, wherein the first layer is directly disposed on the second layer.

3. The solar cell according to claim 1 or 2, wherein the percentage of the crystalline material in the first layer is between 75% and 100%, and the percentage of the crystalline material in the second layer is between 50% and 75%.

4. The solar cell according to claim 1 or 2, wherein the crystalline material of the first layer and the second layer comprises a plurality of crystalline regions disposed in an amorphous matrix.

5. The solar cell according to claim 4, wherein the maximum size of each of the plurality of crystalline regions is less than 15 nanometers.

6. The solar cell according to claim 1 or 2, wherein the forming material of the amorphous matrix has substantially the same chemical composition as the crystalline material.

7. A solar cell according to claim 1 or 2, wherein the crystalline material of the first layer is at least partially formed of at least one of silicon suboxide (SiOx) and silicon carbide (SiC).

8. A solar cell according to claim 1 or 2, wherein the crystalline material of the second layer is at least partially formed of at least one of silicon suboxide (SiOx) and silicon carbide (SiC).

9. The solar cell according to claim 7, wherein the layered structure is disposed on the front side of the silicon substrate, the front side being configured to face a radiation source when the solar cell is in use.

10. A solar cell according to claim 1 or 2, wherein the first layer and the second layer comprise a combined depth of less than 15 nanometers, optionally less than 11 nanometers.

11. A solar cell according to claim 1 or 2, wherein the layered structure comprises: a third layer containing a percentage of crystalline material disposed in an amorphous matrix, the third layer being interposed between the second layer and the surface of the silicon substrate; and wherein the percentage of the crystalline material in the third layer is greater than zero.

12. The solar cell according to claim 11, wherein the layered structure includes: a passivation layer formed of an amorphous material, the passivation layer being interposed between the third layer and the surface of the silicon substrate.

13. The solar cell according to claim 11, wherein the percentage of the crystalline material in the third layer is less than the percentage of the crystalline material in the second layer.

14. The solar cell according to claim 12, wherein the third layer has a depth of less than 5 nanometers, preferably less than 4 nanometers, and at least 1 nanometer, and wherein the passivation layer has a depth of less than 3 nanometers.

15. A solar cell according to claim 1 or 2, wherein the crystalline material in at least one layer of the layered structure is substantially evenly distributed across the depth of the individual layers.

16. A solar cell according to claim 1 or 2, wherein the first layer and the second layer are constructed with conductivity types determined by the included doping atoms, the first layer having a first concentration of doping atoms, and the second layer having a second concentration of doping atoms less than the first concentration.

17. The solar cell according to claim 11, wherein the third layer is constructed with a conductivity type determined by the included doping atoms, and the concentration of the doping atoms in the third layer is less than the concentration of the doping atoms in the second layer.

18. A solar cell according to claim 1 or 2, wherein the layered structure defines a front layered structure disposed on the front side of the silicon substrate, and the first layer and the second layer respectively define a first and a second front layer, wherein the solar cell further includes a back layered structure disposed on a back side of the silicon substrate opposite to the front side; wherein the back layered structure includes a first and a second back layer, each containing a percentage of crystalline material disposed in an amorphous matrix, the second back layer being interposed between the first back layer and the back side of the silicon substrate; wherein the percentage of the crystalline material in the first back layer is greater than the percentage of the crystalline material in the second back layer.

19. The solar cell of claim 18, wherein at least one layer of the front layered structure is configured with a conductivity type that is opposite to the conductivity type of at least one layer of the back layered structure.

20. The solar cell according to claim 18, wherein the silicon substrate is constructed of a negative conductivity type, at least one layer of the front layered structure is constructed of a positive conductivity type, and at least one layer of the back layered structure is constructed of a negative conductivity type.

21. A solar module comprising a plurality of solar cells according to any one of claims 1 to 20, wherein the plurality of solar cells are electrically coupled together.

22. A method of manufacturing a solar cell comprising a layered structure, the method comprising providing a silicon substrate and disposing a layered structure on the surface of the silicon substrate, the layered structure comprising a first layer and a second layer, each comprising a percentage of crystalline material disposed in an amorphous matrix; the step of disposing the layered structure comprising: disposing the second layer on the surface of the silicon substrate; and disposing the first layer on the second layer such that the second layer is interposed between the first layer and the surface of the silicon substrate; wherein the method of disposing the first layer and the second layer comprises constructing the first layer with a percentage of crystalline material greater than the percentage of crystalline material in the second layer; and wherein the percentage of crystalline material in the second layer is greater than zero.

23. The method of claim 22, wherein the layered structure comprises: a third layer comprising a percentage of crystalline material disposed in an amorphous matrix; and a passivation layer formed of the amorphous material; the method comprising, before disposing the first layer and the second layer, disposing the passivation layer on the surface of the silicon substrate; and disposing the third layer on the passivation layer.

24. The method of claim 23, wherein the method comprises constructing the third layer with a percentage of crystalline material less than the percentage of crystalline material in the second layer.

25. The method of any one of claims 22 to 24, wherein the step of configuring the layered structure comprises sequentially depositing layers of the layered structure onto the surface of the silicon substrate using a vapor deposition process.

26. The method of claim 25, wherein the method comprises controlling at least one parameter of the vapor deposition process to determine the percentage of the crystalline material in the first layer and the second layer, wherein the at least one parameter comprises at least one of gas composition, gas flow rate, plasma power level, plasma temperature, temperature and pressure of the deposition chamber.

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