CN214043682U - Heterojunction solar cell - Google Patents

Abstract

The utility model provides a heterojunction solar cell, the heterojunction solar cell that relates to has the first transparent conductive film layer that sets up in silicon substrate illuminated surface one side and sets up in silicon substrate backlight surface one side and the second transparent conductive film layer that the square resistance is less than first transparent conductive film layer square resistance, still be provided with first collecting electrode and second collecting electrode on first transparent conductive film layer and the second transparent conductive film layer respectively, the second collecting electrode has the aluminium auxiliary grid that sets up on the second transparent conductive film layer; the utility model changes the back silver auxiliary grid of the traditional heterojunction solar cell into the aluminum auxiliary grid, which can greatly reduce the manufacturing cost of the heterojunction solar cell; and because the second transparent conductive film layer positioned on the backlight surface has smaller sheet resistance relative to the first transparent conductive film layer positioned on the light receiving surface, even if the traditional back silver auxiliary grid in the heterojunction solar cell is replaced by an aluminum auxiliary grid, the smooth transmission of the current on the back surface of the heterojunction solar cell can be also met.

Description

Heterojunction solar cell

Technical Field

The utility model relates to a photovoltaic field of making especially relates to a heterojunction solar cell.

Background

The heterojunction solar cell is a relatively high-efficiency crystalline silicon solar cell at present, combines the characteristics of a crystalline silicon cell and a silicon-based thin film cell, and has the advantages of short manufacturing process, low process temperature, high conversion efficiency, more generated energy and the like. The heterojunction solar cell has a small temperature degradation coefficient and double-sided power generation, so that the annual power generation amount can be 15-30% higher than that of a common polycrystalline silicon cell under the condition of the same area, and therefore the heterojunction solar cell has great market potential.

The heterojunction solar cell in the prior art sequentially comprises a first collector electrode, a first transparent conductive film layer, a first doped amorphous layer, a first intrinsic amorphous layer, a silicon substrate, a second intrinsic amorphous layer, a second doped amorphous layer, a second transparent conductive film layer and a second collector electrode from one side of a light receiving surface to one side of a backlight surface. The first collector consists of a front silver main grid and a front silver auxiliary grid, and the second collector consists of a back silver main grid and a back silver auxiliary grid; in other words, in the prior art, the first collecting electrode and the second collecting electrode are made of conductive silver paste based on the consideration of reducing the current transmission resistance of the heterojunction solar cell. However, the conductive silver paste has a high purchase price, which is not favorable for reducing the manufacturing cost of the heterojunction solar cell.

In view of the above, there is a need to provide an improved solution to the above problems.

SUMMERY OF THE UTILITY MODEL

The utility model discloses aim at solving one of the technical problem that prior art exists at least, for realizing the utility model purpose of the aforesaid, the utility model provides a heterojunction solar cell, its concrete design as follows.

A heterojunction solar cell comprises a silicon substrate, a first intrinsic amorphous layer and a first doped amorphous layer which are sequentially arranged on one side of a light receiving surface of the silicon substrate, and a second intrinsic amorphous layer and a second doped amorphous layer which are sequentially arranged on one side of a backlight surface of the silicon substrate.

Further, the square resistance of the first transparent conductive film layer is 40-70 omega/□, and the square resistance of the second transparent conductive film layer is 20-40 omega/□.

Further, the thickness of the second transparent conductive film layer is larger than that of the first transparent conductive film layer.

Further, the second transparent conductive film layer comprises an ITO film, an IWO film or an ITiO film, and the first transparent conductive film layer comprises an ITO film, an IWO film or an ITiO film, wherein the carrier concentration of the ITO film, the IWO film or the ITiO film is smaller than that of the second transparent conductive film layer.

Further, the first transparent conductive film layer comprises a first ITO film with the mass ratio of indium oxide to tin oxide being 97:3, and the second transparent conductive film layer comprises a second ITO film with the mass ratio of indium oxide to tin oxide being 97:3 and a third ITO film with the mass ratio of indium oxide to tin oxide being 90: 10.

Further, the first collector electrode is provided with a front main grid and a front auxiliary grid which are arranged on the first transparent conductive film layer, the second collector electrode is further provided with a back main grid which is arranged on the second transparent conductive film layer, and at least one of the front main grid, the front auxiliary grid and the back main grid is a silver-coated nickel particle stacked layer structure, a silver-coated copper particle stacked layer structure, a silver-coated aluminum particle stacked layer structure, a silver-coated glass powder particle stacked layer structure, a nickel-coated carbon particle stacked layer structure or a nickel particle stacked layer structure.

Further, the particle diameters of silver-coated nickel particles in the silver-coated nickel particle stacked layer structure, silver-coated copper particles in the silver-coated copper particle stacked layer structure, silver-coated aluminum particles in the silver-coated aluminum particle stacked layer structure, silver-coated glass powder particles in the silver-coated glass powder particle stacked layer structure, nickel-coated carbon particles in the nickel-coated carbon particle stacked layer structure, and nickel particles in the nickel particle stacked layer structure are 5 to 15 μm.

Further, in the heterojunction solar cell, the silver-coated nickel particle stacked layer structure, the silver-coated copper particle stacked layer structure, the silver-coated aluminum particle stacked layer structure, the silver-coated glass powder particle stacked layer structure, the nickel-coated carbon particle stacked layer structure or the nickel particle stacked layer structure comprises at least two layers of structures in the thickness direction of the silicon substrate, and the projections of the silver-coated nickel particles, the silver-coated copper particles, the silver-coated aluminum particles, the silver-coated glass powder particles, the nickel-coated carbon particles or the nickel particles in the adjacent two layers of structures are in staggered distribution on the plane where the silicon substrate is located.

Furthermore, the heterojunction solar cell also comprises a conductive filling layer arranged at the position of a particle gap in a silver-coated nickel particle stacking layer structure, a silver-coated copper particle stacking layer structure, a silver-coated aluminum particle stacking layer structure, a silver-coated glass powder particle stacking layer structure, a nickel-coated carbon particle stacking layer structure or a nickel particle stacking layer structure.

Further, the conductive filling layer is a nano silver particle filling layer or a nano nickel particle filling layer.

The utility model has the advantages that: in the heterojunction solar cell, the back silver auxiliary grid of the traditional heterojunction solar cell is replaced by the aluminum auxiliary grid, so that the manufacturing cost of the heterojunction solar cell can be greatly reduced; and because the second transparent conductive film layer positioned on the backlight surface has smaller sheet resistance relative to the first transparent conductive film layer positioned on the light receiving surface, even if the traditional back silver auxiliary grid in the heterojunction solar cell is replaced by an aluminum auxiliary grid, the smooth transmission of the current on the back surface of the heterojunction solar cell can be also met.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required to be used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the provided drawings without creative efforts. The front and back sides referred to herein are only defined with respect to the positional relationship in the drawings of the embodiments, that is, the front side corresponds to the upper surface of the drawings, and the back side corresponds to the lower surface of the drawings.

Fig. 1 is a schematic plan view of a light receiving surface side of a heterojunction solar cell according to the present invention;

fig. 2 is a schematic plan view of a back side of the heterojunction solar cell of the present invention;

FIG. 3 is a schematic cross-sectional view of a first embodiment of the heterojunction solar cell of FIG. 1 at the A-A' position;

FIG. 4 is a schematic cross-sectional view of a second embodiment of the heterojunction solar cell of FIG. 1 at the A-A' position;

fig. 5 is a schematic cross-sectional view of a first embodiment of the front side grating of the present invention;

fig. 6 is a schematic cross-sectional view of a second embodiment of the front side grating of the present invention;

fig. 7 is a schematic cross-sectional view of a third embodiment of the front side sub-grid of the present invention.

In the figure, 10 is a silicon substrate, 21 is a first intrinsic amorphous layer, 31 is a first doped amorphous layer, 41 is a first transparent conductive film layer, 51 is a first collector, 511 is a front side sub-gate, 512 is a front side main gate, 22 is a second intrinsic amorphous layer, 32 is a second doped amorphous layer, 42 is a second transparent conductive film layer, 421 is a second ITO film, 422 is a third ITO film, 52 is a second collector, 521 is an aluminum sub-gate, 522 is a back side main gate, 500 is a grain body, 501 is a cladding layer, 502 is a core, 503 is a conductive filling layer.

Detailed Description

The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative work belong to the protection scope of the present invention.

The utility model provides a heterojunction solar cell, it is shown with reference to fig. 3, heterojunction solar cell includes silicon substrate 10, sets gradually in first intrinsic amorphous layer 21 and the first impurity-doped amorphous layer 31 of silicon substrate 10 sensitive surface one side, sets gradually in second intrinsic amorphous layer 22 and the second impurity-doped amorphous layer 32 of silicon substrate 10 shady face one side. Preferably, the silicon substrate 10 according to the present invention is a single crystal silicon substrate.

The utility model relates to a heterojunction solar cell is still including setting up the first transparent conductive film layer 41 on first doping amorphous layer 31 and setting up the transparent conductive film layer 42 of second on second doping amorphous layer 32, and wherein, the square resistance of the transparent conductive film layer 42 of second is less than the square resistance of first transparent conductive film layer 41.

In the specific implementation process, the first intrinsic amorphous layer 21, the second intrinsic amorphous layer 22, the first doped amorphous layer 31 and the second doped amorphous layer 32 are all formed by a PECVD process; the first transparent conductive film 41 and the second transparent conductive film 42 are formed on the surface of the first doped amorphous layer 31 and the surface of the second doped amorphous layer 32 by PVD processes, respectively.

As shown in fig. 1 and fig. 2, in the present invention, the first transparent conductive film layer 41 and the second transparent conductive film layer 42 are further respectively provided with a first collector 51 and a second collector 52, wherein the second collector 52 has an aluminum sub-grid 521 disposed on the second transparent conductive film layer 42.

The utility model relates to an among the heterojunction solar cell, the vice bars of back silver with traditional heterojunction solar cell are changed to aluminium vice bars 521, can reduce heterojunction solar cell's cost of manufacture by a wide margin, particularly, aluminium vice bars adopts electrically conductive aluminium thick liquid preparation to form, and its relatively electrically conductive silver thick liquid has lower acquisition cost. In addition, since the second transparent conductive film layer 42 on the backlight surface has a smaller sheet resistance than the first transparent conductive film layer 41 on the light receiving surface, even if the conventional back silver sub-grid in the heterojunction solar cell is replaced with the aluminum sub-grid 521, smooth transmission of the current on the back surface of the heterojunction solar cell can be satisfied, that is, the series resistance of the heterojunction solar cell is not increased compared with the prior art.

It is understood that the light receiving surface of the silicon substrate 10 according to the present embodiment is a surface of the heterojunction solar cell directly receiving sunlight, and the back surface is a surface of the heterojunction solar cell not directly receiving sunlight, i.e., a surface opposite to the light receiving surface. The first and second intrinsic amorphous layers 21 and 22 are intrinsic amorphous silicon. The doping types of the first doped amorphous layer 31 and the second doped amorphous layer 32 are opposite, wherein one of the first doped amorphous layer and the second doped amorphous layer is doped with N type, namely phosphorus is adopted for doping; the other is P-type doping, namely boron doping is adopted.

In the present invention, although the silicon substrate 10 may be a P-type silicon substrate, an N-type single crystal substrate silicon may be selected; however, in a preferred embodiment of the present invention, the silicon substrate 10 is an N-type silicon substrate. Typically, the silicon substrate 10 is 90-16um thick with sides 156-210 mm. Further preferably, the first doped amorphous layer 31 is an N-type doped amorphous layer, and the second doped amorphous layer 32 is a P-type doped amorphous layer.

In one embodiment, the sheet resistance of the first transparent conductive film 41 is 40-70 Ω/□, and the sheet resistance of the second transparent conductive film 42 is 20-40 Ω/□.

In order to make the sheet resistance of the second transparent conductive film 42 smaller than that of the first transparent conductive film 41, in practical implementation, the thickness of the second transparent conductive film 42 is greater than that of the first transparent conductive film 41. In some embodiments, the thickness of the first transparent conductive film layer 41 is usually 80-120nm, and correspondingly, the thickness of the second transparent conductive film layer 41 is 120-200 nm.

Further, current carrying of the first transparent conductive film layer 41The sub-concentration is less than the carrier concentration of the second transparent conductive film layer 42, so that the first transparent conductive film layer 41 has better light transmittance than the second transparent conductive film layer 42, and the second transparent conductive film layer 42 has excellent conductive performance. In the specific implementation process, the carrier concentration of the first transparent conductive film layer 41 is 1.0E20/cm^-3～2.5E20/cm^-3The carrier concentration of the second transparent conductive film layer 42 is 5.0E20/cm^-3～1.0E21/cm^-3. For the heterojunction solar cell, the first transparent conductive film layer 41 has a better light transmittance than the second transparent conductive film layer 42, so that the short-circuit current of the heterojunction solar cell can be effectively ensured.

Generally, the first transparent conductive film layer 41 and the second transparent conductive film layer 42 are each specifically composed of an ITO film, an IWO film, or an ITiO film. Wherein, ITO refers to tin-doped indium oxide film, IWO refers to tungsten-doped indium oxide, and ITIO refers to titanium-doped indium oxide.

As a preferred embodiment, referring to fig. 5, the first transparent conductive film layer 41 includes a first ITO film with a mass ratio of indium oxide to tin oxide of 97:3, and the second transparent conductive film layer 42 includes a second ITO film 421 with a mass ratio of indium oxide to tin oxide of 97:3, and a third ITO film 422 with a mass ratio of indium oxide to tin oxide of 90: 10.

For the ITO film with the mass ratio of indium oxide to tin oxide being 97:3, the ITO film has higher mobility, the first transparent conductive film layer 41 is the ITO film with the mass ratio of indium oxide to tin oxide being 97:3, and the conductivity of the first transparent conductive film layer 41 can be improved as much as possible on the premise that the carrier concentration is lower; for the ITO film with the mass ratio of indium oxide to tin oxide of 90:10, the carrier concentration is higher, the second transparent conductive film layer 42 is formed by the second ITO film 421 and the third ITO film 422, and the mobility of the second transparent conductive film layer 42 can be further optimized while the carrier concentration is higher.

In the embodiment shown in FIG. 5, the thickness ratio and the layer sequence of the second ITO film 421 to the third ITO film 422 can be adjusted as required. For example, the thicknesses of the second ITO film 421 and the third ITO film 422 may be equal, and the order of layering of the second ITO film 421 and the third ITO film 422 may be different from the layered structure in fig. 5.

It is understood that, in other embodiments of the present invention, the film layers of the first transparent conductive film layer 41 and the second transparent conductive film layer 42 may not be limited to the number of film layers illustrated in fig. 5.

As shown in fig. 1 and 2, the first collector 51 of the present invention has a front main grid 512 and a front sub-grid 511 disposed on the first transparent conductive film 41, and the second collector 52 further has a back main grid 522 disposed on the second transparent conductive film 42. As the utility model discloses a preferred, positive main grid 512, positive vice grid 511 and back main grid 522 in at least one pile up the layer structure for silver-clad nickel granule, silver-clad copper granule piles up the layer structure, silver-clad aluminium granule piles up the layer structure, silver-clad glass powder granule piles up the layer structure, nickel-clad carbon granule piles up the layer structure or nickel granule piles up the layer structure.

It understands comparatively easily the utility model discloses in, silver-clad nickel granule piles up the rete that the layered structure indicates to pile up and form by a plurality of silver-clad nickel granules, and is corresponding, and silver-clad copper granule piles up the layered structure, silver-clad aluminium granule piles up the layered structure, silver-clad glass powder granule piles up the layered structure, nickel-clad carbon granule piles up the layered structure and nickel granule piles up the layered structure and also indicate respectively to pile up and form the rete by corresponding granule.

Referring to the embodiments shown in fig. 5, 6 and 7, which show several different implementation structures of the front side sub-gate 511, some implementation structures of the front side main gate 512 and the back side main gate 522 may refer to the implementation structures of the front side sub-gate 511 shown in fig. 5, 6 and 7, and will not be described further.

As shown in the figure, the stacked layer structure of particles in the present invention is formed by stacking a plurality of particle bodies 500, wherein the particle bodies 500 are silver-coated nickel particles, silver-coated copper particles, silver-coated aluminum particles, silver-coated glass powder particles or nickel-coated carbon particles, and the particle bodies 500 include a coating layer 501 and a core 502 located inside the coating layer 501. When the coating layer 501 is a silver metal layer, the core 502 is a nickel metal core, a copper metal core, an aluminum metal core or a glass powder core; when the clad layer 501 is a nickel metal layer, the core 502 is a carbon core.

The utility model relates to an among the heterojunction solar cell, set up the mode more than adopting except that the electrode grid line (including positive main grid 512, positive auxiliary grid 511 and back main grid 522) of aluminium auxiliary grid 521, for heterojunction solar cell's collecting electrode preparation provides more choices, can effectively reduce heterojunction solar cell's cost of manufacture, and can improve the problem that low temperature conductive silver thick liquid contact resistivity is high among the prior art, reduced the loss of fill factor FF.

Preferably, in the utility model discloses in, silver-clad nickel granule among the silver-clad nickel granule stacked layer structure, silver-clad copper granule stacked layer structure in silver-clad nickel granule, silver-clad copper granule, silver-clad aluminum granule stacked layer structure in silver-clad aluminum granule, silver-clad glass powder granule stacked layer structure in silver-clad glass powder granule, nickel-clad carbon granule stacked layer structure in nickel-clad carbon granule and nickel granule stacked layer structure in the particle diameter of nickel granule is 5-15 μm. Referring to fig. 5 to 7, the particle size of the particle body 500 is 5 to 15 μm.

In some embodiments of the present invention, when the electrode grid line except the aluminum sub-grid 521 contains the silver-coated nickel particles, the silver-coated copper particles, or the silver-coated aluminum particles, the mass ratio of silver in the silver-coated nickel particles, the silver-coated copper particles, and the silver-coated aluminum particles is 15% to 25%; when the electrode grid lines except the aluminum auxiliary grid 521 contain silver-coated glass powder particles, the mass ratio of silver in the silver-coated glass powder particles is 50-75%; when the electrode grid lines except the aluminum auxiliary grid 521 contain nickel-coated carbon particle components, the mass percentage of nickel in the nickel-coated carbon particles is 60-75%.

As shown in fig. 5, in the implementation process of the present invention, the stacked layer structure of silver-coated nickel particles, the stacked layer structure of silver-coated copper particles, the stacked layer structure of silver-coated aluminum particles, the stacked layer structure of silver-coated glass powder particles, the stacked layer structure of nickel-coated carbon particles, or the stacked layer structure of nickel particles in the heterojunction solar cell includes at least two layers in the thickness direction of the silicon substrate; and the projections of the silver-coated nickel particles, the silver-coated copper particles, the silver-coated aluminum particles, the silver-coated glass powder particles, the nickel-coated carbon particles or the nickel particles in the two adjacent layers of structures on the plane of the silicon substrate 10 are distributed in a staggered manner. By such an arrangement, more contact points are formed between two adjacent layers of particle bodies 500, and the electrode grid lines except the aluminum auxiliary grid 521 have a more stable structure.

Further preferably, as shown in fig. 5, in the adjacent two-layer structure, the number of silver-coated nickel particles, silver-coated copper particles, silver-coated aluminum particles, silver-coated glass frit particles, nickel-coated carbon particles or nickel particles in a layer distant from the silicon substrate is smaller than the number of silver-coated nickel particles, silver-coated copper particles, silver-coated aluminum particles, silver-coated glass frit particles, nickel-coated carbon particles or nickel particles in a layer close to the silicon substrate.

As shown in fig. 5, since the number of the particle bodies 500 in a layer distant from the silicon substrate is smaller than the number of the particle bodies 500 in a layer close to the silicon substrate, the particle bodies 500 in a layer distant from the silicon substrate can be stacked more stably on the particle bodies 500 in a layer close to the silicon substrate.

In order to make the sub-grid have more excellent conductivity and structural stability, in some embodiments of the present invention, referring to fig. 6, the heterojunction solar cell further includes a conductive filling layer 503 disposed at a position of a particle gap in the silver-coated nickel particle stacked layer structure, the silver-coated copper particle stacked layer structure, the silver-coated aluminum particle stacked layer structure, the silver-coated glass powder particle stacked layer structure, the nickel-coated carbon particle stacked layer structure, or the nickel particle stacked layer structure. Preferably, the conductive filling layer 503 is a silver conductive filling layer or a nickel conductive filling layer.

It can be understood that, since the particle bodies 500 usually adopt an encapsulation structure, the particle size of the particle bodies is often relatively large, so when a plurality of particle bodies 500 are stacked, a large gap is formed between two or more adjacent particle bodies 500, and the conductivity and the structural stability of the corresponding sub-grid are affected. In the embodiment shown in fig. 6, each metal particle of the conductive filling layer 503 is often a single metal, so that each metal particle forms a smaller particle size, and thus can be better filled at the gap position of the plurality of particle bodies 500. In the specific implementation process, the metal particles constituting the conductive filling layer preferably have a particle size in the range of 50 to 200 nm.

Preferably, the conductive filling layer is a nano silver particle filling layer or a nano nickel particle filling layer.

As can be seen from fig. 6 and 7, the width of the corresponding electrode grid line can be changed by changing the number of the particle bodies 500 arranged in the width direction of the electrode grid line.

It is understood that in other embodiments of the present invention, only one of the first transparent conductive film layer 41 and the second transparent conductive film layer 42 may have an electrode grid line on its surface, and the other may have a grid line structure, such as a silver grid, similar to the conventional art.

Particularly, for the electrode grid line except the aluminum auxiliary grid 521 of the utility model, in the silver-coated nickel particles, the silver-coated copper particles and the silver-coated aluminum particles, the nickel, the copper and the aluminum are respectively adopted to replace part of the silver in the traditional low-temperature silver paste, so that the manufacturing cost of the conductive paste can be greatly reduced; and the form of coating silver outside can ensure the conductivity of the corresponding electrode grid line. In particular, in the silver-coated glass frit particles, due to the presence of the glass frit, better contact can be formed between the silver-coated glass frit particles and the first transparent conductive film 41 or the second transparent conductive film 42 when the corresponding electrode grid lines are cured and molded, so that contact resistance is reduced. In addition, the nickel-coated carbon particles and the nickel particles completely replace silver particles designed in the prior art, and the manufacturing cost of the conductive paste can be effectively reduced.

In the present invention, it is further preferable that a projected area of the front surface sub-grid 511 on the plane of the silicon substrate 10 is smaller than a projected area of the aluminum sub-grid 521 on the plane of the silicon substrate 10.

In an embodiment, the distance between two adjacent front side sub-grids 511 on the light receiving side of the silicon substrate 10 is greater than the distance between two adjacent aluminum sub-grids 521 on the backlight side of the silicon substrate 10, that is, the number of front side sub-grids 511 on the light receiving side is less than the number of aluminum sub-grids 521 on the backlight side, so that the shielding area of the front side sub-grids 511 on the light receiving side is smaller than that of the aluminum sub-grids 521 on the backlight side. Therefore, in a specific application scene, the effective illumination area of the light receiving surface can be increased and the photo-generated current can be increased due to the large distance between two adjacent auxiliary grids of the light receiving surface; the series resistance of the heterojunction solar cell can be further reduced due to the small distance between the two adjacent aluminum auxiliary grids 521 on the backlight surface, and the photoelectric conversion efficiency of the heterojunction solar cell can be effectively optimized due to the combination of the two.

In specific implementation, the distance between two adjacent front-side sub-grids 511 on one side of the light receiving surface of the silicon substrate 10 is 1.5-2.0 mm; the distance between two adjacent aluminum sub-grids 521 on the backlight side of the silicon substrate 10 is 1.0-1.9 mm.

Furthermore, in the present invention, the aluminum sub-grid 521 has a width of 40-50 μm and a thickness of 12-18 μm.

Preferably, the first intrinsic amorphous layer 21 and the second intrinsic amorphous layer 22 according to the present invention each include at least two intrinsic amorphous silicon films stacked on each other, and in the specific implementation process, by controlling the characteristics of each intrinsic amorphous silicon film, the first intrinsic amorphous layer 21 and the second intrinsic amorphous layer 22 having better overall performance can be formed.

Specifically, in the present invention, the hydrogen content of the intrinsic amorphous silicon film near the single crystal silicon substrate 10 in the first intrinsic amorphous layer 21 is higher than the hydrogen content of the intrinsic amorphous silicon film far from the single crystal silicon substrate, and the hydrogen content of the intrinsic amorphous silicon film near the single crystal silicon substrate 10 in the second intrinsic amorphous layer 22 is higher than the hydrogen content of the intrinsic amorphous silicon film far from the single crystal silicon substrate.

It can be easily understood that the intrinsic amorphous silicon films closer to the single crystal silicon substrate 10 of the first intrinsic amorphous layer 21 and the second intrinsic amorphous layer 22 have more obvious passivation effect on the single crystal silicon substrate 10, and the intrinsic amorphous silicon films closer to the single crystal silicon substrate 10 have higher hydrogen content, so that the first intrinsic amorphous layer 21 and the second intrinsic amorphous layer 22 have the optimal passivation effect on the single crystal silicon substrate 10.

As a preferred embodiment, when the first intrinsic amorphous layer 21 and the second intrinsic amorphous layer 22 respectively include three intrinsic amorphous silicon films stacked, the hydrogen content of the three intrinsic amorphous silicon films of the first intrinsic amorphous layer 21 and the second intrinsic amorphous layer 22 respectively ranges from 20% to 40%, from 10% to 25%, and from 8% to 20% in this order in a direction away from the single crystal silicon substrate 10.

Preferably, the first doped amorphous layer 31 according to the present invention includes a first doped amorphous silicon film on the surface of the first intrinsic amorphous layer 21 and a doped amorphous silicon oxide film on the surface of the first doped amorphous silicon film.

The doped amorphous silicon oxide has more excellent light transmittance than the doped amorphous silicon. The first doped amorphous layer involved in the prior art is generally a single-layer doped amorphous silicon film structure; in this embodiment, the first doped amorphous layer 31 is designed as a double-layer film, wherein the first doped amorphous silicon film can ensure that the first doped amorphous layer 31 is in good contact with the first intrinsic amorphous layer 21, and the doped amorphous silicon oxide film is equivalent to replace a part of doped amorphous silicon in the prior art with doped amorphous silicon oxide having high light transmittance, so that the overall light transmittance of the first doped amorphous layer 31 can be improved, the loss of sunlight passing through the first intrinsic amorphous layer and the first doped amorphous layer can be reduced, the short-circuit current of the heterojunction solar cell can be further improved, and the optimization of the photoelectric conversion efficiency is facilitated.

Based on the cooperation of first doping amorphous silicon film, doping amorphous silicon oxide film promptly, the utility model provides a heterojunction solar cell has comparatively excellent optics and electrical property.

In a specific implementation process, the thickness of the first doped amorphous silicon film is less than or equal to that of the doped amorphous silicon oxide film; preferably, the thickness of the first doped amorphous silicon film is generally less than the thickness of the doped amorphous silicon oxide film. Thus, while ensuring a good contact between the first doped amorphous layer 31 and the first intrinsic amorphous layer 21, the first doped amorphous layer 31 can have a good transmittance to a great extent.

In other embodiments of the present invention, the first doped amorphous layer 31 further comprises a second doped amorphous silicon film on the surface of the doped amorphous silicon oxide film. The doped amorphous silicon generally has a relatively excellent conductivity, and the second doped amorphous silicon film is disposed to enable the first doped amorphous layer 31 and the first transparent conductive film layer 41 to have a relatively good contact therebetween, so as to further reduce the contact resistance, and enable the cell to have a higher fill factor. In particular, the doping concentration of the second doped amorphous silicon film may be higher than that of the first doped amorphous silicon film.

In this embodiment, the thickness of the second doped amorphous silicon film is less than or equal to the thickness of the doped amorphous silicon oxide film; preferably, the thickness of the second doped amorphous silicon film is also generally smaller than that of the doped amorphous silicon oxide film, thereby allowing the first doped amorphous layer 31 to have a better light transmittance.

Further, in still other embodiments of the present invention, the second doped amorphous layer 32 comprises a third doped amorphous silicon film on the surface of the second intrinsic amorphous layer 22 and a fourth doped amorphous silicon film with a doping concentration higher than that of the third doped amorphous silicon film on the surface of the third doped amorphous silicon film.

Preferably, the carrier concentration of the fourth doped amorphous silicon film is 5E 19-5E 21/cm 3. Accordingly, the carrier concentration of the third doped amorphous silicon film is set to 5E 18-5E 19/cm3

In this embodiment, the third doped amorphous silicon film has a relatively low doping concentration, so that the influence on the second intrinsic amorphous layer 22 can be reduced, the lattice distortion of the second intrinsic amorphous layer 22 can be reduced, and the passivation effect of the back surface of the heterojunction solar cell can be effectively ensured; the fourth doped amorphous silicon film has a relatively high doping concentration, so that the contact between the second doped amorphous layer 32 and the second transparent conductive film can be improved, the contact resistance between the second doped amorphous layer and the second transparent conductive film can be reduced, and the cell filling factor can be improved.

In the utility model, the thickness of the third doped amorphous silicon film is less than or equal to that of the fourth doped amorphous silicon film; preferably, the thickness of the third doped amorphous silicon film is generally smaller than that of the fourth doped amorphous silicon film.

Preferably, in the present invention, the sum of the thicknesses of the first intrinsic amorphous layer 21 and the first doped amorphous layer 31 is smaller than the sum of the thicknesses of the second intrinsic amorphous layer 22 and the second doped amorphous layer 32.

For the heterojunction solar cell, the influence of the light absorption effect of the light receiving surface on the photoelectric conversion efficiency of the cell is far larger than the influence of the light absorption effect of the backlight surface on the photoelectric conversion efficiency of the cell, and because the sum of the thicknesses of the first intrinsic amorphous layer 21 and the first doped amorphous layer 31 is smaller than the sum of the thicknesses of the second intrinsic amorphous layer 22 and the second doped amorphous layer 32, the loss of sunlight on the light receiving surface when the sunlight passes through the first intrinsic amorphous layer 21 and the first doped amorphous layer 31 can be effectively reduced, the short-circuit current of the heterojunction solar cell can be improved, and the heterojunction solar cell has better photoelectric conversion efficiency.

In some more specific embodiments of the present invention, the sum of the thicknesses of the first intrinsic amorphous layer 21 and the first doped amorphous layer 31 is 6-21nm, and the sum of the thicknesses of the second intrinsic amorphous layer 22 and the second doped amorphous layer 32 is 7-30 nm.

It is further preferable that the thickness of the first intrinsic amorphous layer 21 is less than or equal to the thickness of the second intrinsic amorphous layer 22, and the thickness of the first doped amorphous layer 31 is less than or equal to the thickness of the second doped amorphous layer 32.

In specific implementation, the thickness of the first doped amorphous layer 31 is 3-15nm, and the thickness of the second doped amorphous layer 32 is 3-20 nm. Accordingly, in the embodiment shown in FIG. 1, the first intrinsic amorphous layer 21 has a thickness of 3-6nm and the second intrinsic amorphous layer 22 has a thickness of 4-10 nm.

It is further preferable that the thickness of the first doped amorphous layer 31 is 4 to 5nm and the thickness of the second doped amorphous layer 32 is 4 to 5 nm. Accordingly, in the embodiment shown in FIG. 1, the first intrinsic amorphous layer 21 has a thickness of 4-5nm and the second intrinsic amorphous layer 22 has a thickness of 5-6 nm.

The above list of details is only for the practical implementation of the present invention, and they are not intended to limit the scope of the present invention, and all equivalent implementations or modifications that do not depart from the technical spirit of the present invention should be included in the scope of the present invention.

Claims (9)

1. A heterojunction solar cell comprises a silicon substrate, a first intrinsic amorphous layer and a first doped amorphous layer which are sequentially arranged on one side of a light receiving surface of the silicon substrate, and a second intrinsic amorphous layer and a second doped amorphous layer which are sequentially arranged on one side of a backlight surface of the silicon substrate.

2. The heterojunction solar cell of claim 1, wherein the sheet resistance of the first transparent conductive film layer is 40-70 Ω/□, and the sheet resistance of the second transparent conductive film layer is 20-40 Ω/□.

3. The heterojunction solar cell of claim 1, wherein the thickness of the second transparent conductive film layer is greater than the thickness of the first transparent conductive film layer.

4. The heterojunction solar cell of any of claims 1-3, wherein the second transparent conductive film layer comprises an ITO film, an IWO film, or an ITiO film, and the first transparent conductive film layer comprises an ITO film, an IWO film, or an ITiO film having a carrier concentration less than the carrier concentration of the second transparent conductive film layer.

5. The heterojunction solar cell of any of claims 1 to 3, wherein the first collector electrode has a front primary grid and a front secondary grid disposed on the first transparent conductive film layer, and the second collector electrode further has a back primary grid disposed on the second transparent conductive film layer, wherein at least one of the front primary grid, the front secondary grid and the back primary grid is a silver-coated nickel particle stacked layer structure, a silver-coated copper particle stacked layer structure, a silver-coated aluminum particle stacked layer structure, a silver-coated glass powder particle stacked layer structure, a nickel-coated carbon particle stacked layer structure or a nickel particle stacked layer structure.

6. The heterojunction solar cell of claim 5, wherein the particle size of the silver-coated nickel particles in the silver-coated nickel particle stacked layer structure, the silver-coated copper particles in the silver-coated copper particle stacked layer structure, the silver-coated aluminum particles in the silver-coated aluminum particle stacked layer structure, the silver-coated glass powder particles in the silver-coated glass powder particle stacked layer structure, the nickel-coated carbon particles in the nickel-coated carbon particle stacked layer structure, and the nickel particles in the nickel particle stacked layer structure is 5-15 μm.

7. The heterojunction solar cell of claim 6, wherein the stacked layer structure of silver-coated nickel particles, the stacked layer structure of silver-coated copper particles, the stacked layer structure of silver-coated aluminum particles, the stacked layer structure of silver-coated glass powder particles, the stacked layer structure of nickel-coated carbon particles or the stacked layer structure of nickel particles in the heterojunction solar cell comprises at least two layers of structures in the thickness direction of the silicon substrate, and projections of the silver-coated nickel particles, the silver-coated copper particles, the silver-coated aluminum particles, the silver-coated glass powder particles, the nickel-coated carbon particles or the nickel particles in the adjacent two layers of structures on the plane of the silicon substrate are distributed in a staggered manner.

8. The heterojunction solar cell of claim 5, further comprising a conductive filler layer disposed at a particle gap location in the silver-clad nickel particle stacked layer structure, the silver-clad copper particle stacked layer structure, the silver-clad aluminum particle stacked layer structure, the silver-clad glass frit particle stacked layer structure, the nickel-clad carbon particle stacked layer structure, or the nickel particle stacked layer structure.

9. The heterojunction solar cell of claim 8, wherein the conductive filler layer is a nano-silver particle filler layer or a nano-nickel particle filler layer.

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