CN111613678A - A solar cell structure - Google Patents

Abstract

The invention provides a solar cell structure, comprising: a silicon substrate, a doping layer, a passivation film layer and an electrode device arranged in sequence from the silicon substrate outwards; the doping layer includes a first doping region and several second doping regions The first doped region and the second doped region have the same conductivity type; the doping concentration of the second doped region is higher than that of the first doped region; the electrode device is the same as the first doped region and the second doped region. Both doped regions are in contact. In the solar cell structure provided by the present invention, by arranging a second doping region with a higher doping concentration in the doping layer, the concentration of carriers is greatly increased, and the resistivity of the second doping region is also decreased, thus increasing the current collection capability. At the same time, the spacing between the metal electrodes in the electrode device can be increased, thereby reducing the carrier recombination rate in the contact area between the metal electrode and the semiconductor, and finally improving the efficiency of the battery.

Description

A solar cell structure

technical field

The present invention relates to the technical field of photovoltaic power generation, in particular, to a solar cell structure.

Background technique

At present, the common structure of solar cells is to prepare a doped layer on the surface of the semiconductor, and then set a passivation layer and electrodes on it. not tall. In order to improve the current collection capability, the metal electrode area ratio of the battery is usually set higher in the prior art.

And the area ratio of the metal electrode on the battery surface is too high, which will cause some other adverse consequences. For example, due to the extremely high recombination rate in the contact area between the metal electrode and the semiconductor, the battery carrier recombination will be serious, and the larger the area ratio of the metal electrode, the greater the metal recombination, and the greater the impact on the battery efficiency.

SUMMARY OF THE INVENTION

In view of this, the present invention proposes a solar cell structure, aiming at solving the problem of high carrier recombination rate in existing cells.

In one aspect, the present invention provides a solar cell structure, comprising: a silicon substrate, a doping layer, a passivation film layer and an electrode device arranged in sequence from the silicon substrate outwards; the doping layer includes a first doping layer region and several second doping regions, and the first doping region and the second doping region have the same conductivity type; the doping concentration of the second doping region is higher than that of the first doping region doping concentration; the electrode device is in contact with both the first doping region and the second doping region.

Further, in the above solar cell structure, each of the second doping regions is distributed in the first doping region at intervals.

Further, in the above solar cell structure, the width of each of the second doped regions is smaller than the width of the adjacent first doped regions.

Further, in the above solar cell structure, on the first doped region, a plurality of the second doped regions are respectively arranged at intervals along the length direction of the electrode grid lines in the electrode device, and are located on different electrode grid lines. The corresponding two second doped regions below are separated from each other.

Further, in the above solar cell structure, the second doping regions located under the different electrode grid lines are arranged at equal intervals.

Further, in the above solar cell structure, the second doped regions located under the same electrode grid line are arranged at equal intervals.

Further, in the above solar cell structure, the electrode grid lines in the electrode device are arranged at an angle with the second doped region.

Further, in the above solar cell structure, the electrode grid lines in the electrode device are arranged perpendicular to the second doped region.

Further, in the above solar cell structure, the second doped region is a strip-shaped structure, and each of the second doped regions is in contact with at least a section of the electrode grid line.

Further, in the above solar cell structure, the width of each of the second doping regions is 20-300 μm; the spacing between the second doping regions is 300-2000 μm.

Further, in the above solar cell structure, the doping concentration of the first doping region is 5×10 ¹⁸ to 5×10 ²⁰ /cm ³ ; the doping concentration of the second doping region is 1×10 ¹⁹ to 5×10 ²¹ /cm ³ .

Further, in the above solar cell structure, the spacing between every two electrode grid lines in the electrode device is 1-4 mm.

Further, in the above solar cell structure, the passivation film layer is made of one or more of silicon nitride, silicon oxide, silicon oxynitride, aluminum oxide and silicon carbide.

Compared with the prior art, the beneficial effect of the present invention is that, in the solar cell structure provided by the present invention, the concentration of carriers is greatly improved by arranging a second doping region with a higher doping concentration in the doping layer. The resistivity of the second doped region is also reduced, thus increasing the current collection capability. At the same time, the distance between the metal electrodes in the electrode device can be increased to reduce the contact area between the metal electrode and the doped layer. Since the area ratio of the metal electrode is relatively reduced, the contact area between the metal electrode and the doped layer is reduced, thereby reducing the metal electrode. The carrier recombination rate in the contact area with the semiconductor also ultimately improves the efficiency of the cell.

Description of drawings

Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The drawings are for the purpose of illustrating preferred embodiments only and are not to be considered limiting of the invention. Also, the same components are denoted by the same reference numerals throughout the drawings. In the attached image:

1 is a partial schematic diagram of a solar cell structure in an embodiment of the present invention;

FIG. 2 is a partial schematic diagram of the solar cell structure after omitting the surface passivation film layer in the embodiment of the present invention;

3 is a schematic diagram of a front electrode in a specific embodiment of the present invention;

4 is a schematic diagram of a back electrode in a specific embodiment of the present invention;

5 is another schematic diagram of a back electrode in an embodiment of the present invention;

6 is a schematic diagram of a front electrode in another specific embodiment of the present invention;

7 is a schematic structural diagram of a solar cell composed of a solar cell structure in an embodiment of the present invention;

FIG. 8 is another structural schematic diagram of the solar cell showing the surface passivation film layer in FIG. 7;

FIG. 9 is another schematic diagram of a solar cell composed of the solar cell structure in the embodiment of the present invention.

Among them, 1 is the silicon substrate, 2 is the first doping region, 3 is the second doping region, 5 is the passivation anti-reflection film, 6 is the backside passivation film, 7 is the negative electrode grid line, and 7' is the positive electrode The gate line, 8 is the backside passivation film opening area, 9 is the electrode containing aluminum, 10 is the positive electrode connecting electrode, and 11 is the negative electrode connecting electrode.

Detailed ways

Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be embodied in various forms and should not be limited by the embodiments set forth herein. Rather, these embodiments are provided so that the present disclosure will be more thoroughly understood, and will fully convey the scope of the present disclosure to those skilled in the art. It should be noted that the embodiments of the present invention and the features of the embodiments may be combined with each other under the condition of no conflict. The present invention will be described in detail below with reference to the accompanying drawings and in conjunction with the embodiments.

Referring to FIG. 1 and FIG. 2, the solar cell structure according to the embodiment of the present invention includes: a silicon substrate 1, a doped layer, a passivation film layer and an electrode device arranged in order from the silicon substrate to the outside; the doped layer includes a first A doping region 2 and several second doping regions 3, and the first doping region 2 and the second doping region 3 have the same conductivity type; the doping concentration of the second doping region 3 is high The doping concentration of the first doped region 2 ; the electrode device is in contact with both the first doped region 2 and the second doped region 3 .

Specifically, the silicon substrate may be a p-type silicon substrate or an n-type silicon substrate. The doping layer, the passivation film layer and the electrode device can be stacked and disposed outwardly from the front or back of the silicon substrate 1 . Correspondingly, the electrode device in this embodiment refers to a front electrode or a back electrode.

In a specific implementation of this embodiment, referring to FIG. 3 , the front electrode may include: a plurality of negative electrode grid lines 7 and a negative electrode connection electrode 11 . The number of negative electrode grid lines 7 and negative electrode connecting electrodes 11 can be determined according to the actual situation. For example, 100 negative electrode grid lines 7 and 4 negative electrode connecting electrodes 11 are selected, and the negative electrode connecting electrodes 11 are perpendicular to the negative electrode grid lines 7 And the two are connected at the intersection. Wherein, the distance between each two electrode grid lines can be 1-4mm, such as 1mm, 2mm, etc. Since the second doping region with higher doping concentration can enhance the conduction effect, the distance between the electrode grid lines can be appropriately increased. For example, the distance between every two electrode grid lines can be set to 4mm.

Referring to FIGS. 4-5 , the back electrode may include: an aluminum-containing electrode 9 and a positive electrode connection electrode 10 . The passivation film layer may be a front passivation anti-reflection film 5 disposed on the front side of the silicon substrate or a backside passivation film 6 disposed on the back side of the silicon substrate. Both the front passivation anti-reflection film 5 and the back passivation film 6 may be made of one or more of silicon nitride, silicon oxide, silicon oxynitride, aluminum oxide and silicon carbide.

In another specific embodiment of the present invention, referring to FIG. 6 , the front electrode may include: a plurality of positive electrode grid lines 7 ′ and a positive electrode connection electrode 10 . Referring again to FIG. 3 , the back electrode may include a number of negative electrode grid lines 7 and a negative electrode connection electrode 11 . The specific settings of the front electrode and the back electrode are the same as those in the above-mentioned embodiment, which will not be repeated here.

The doping layer includes a first doping region 2 and a plurality of second doping regions 3, and the doping concentration of each second doping region 3 can be kept the same, wherein the doping concentration of the first doping region 2 can be 5 ×10 ¹⁸ to 5 × 10 ²⁰ /cm ³ , preferably 10 ¹⁹ to 2 × 10 ²⁰ /cm ³ ; more preferably 2 × 10 ¹⁹ to 6 × 10 ¹⁹ /cm ³ , for example, in actual production, the first The doping concentration of one doped region 2 can be 5×10 ¹⁸ /cm ³ , 5×10 ¹⁹ /cm ³ , 5×10 ²⁰ /cm ³ , etc.; the doping concentration of the second doped region 3 can be 1×10 ¹⁹ to 5×10 ²¹ /cm ³ , preferably 5×10 ¹⁹ to 3×10 ²¹ /cm ³ ; more preferably 2×10 ¹⁹ to 6×10 ²⁰ /cm ³ ; During fabrication, the doping concentration of the second doping region 3 may be 1×10 ¹⁹ /cm ³ , 5×10 ¹⁹ /cm ³ , 1×10 ²¹ /cm ³ , 5×10 ²¹ /cm ³ Wait. It should be noted that, in this embodiment, the doping concentration refers to the number of atoms of doping elements in the doping area per cubic centimeter. Since the doping concentration of the second doping region 3 is relatively high, the carrier concentration is greatly increased, and the resistivity of the second doping region 3 is also reduced, which is beneficial to increase the current collection capability; therefore, the electrode devices can be appropriately increased The distance between the metal electrodes in the middle is beneficial to reduce the carrier recombination rate in the contact area between the metal electrode and the semiconductor. The conductivity types of the first doped region 2 and the second doped region 3 are the same, and both may be n-type or both may be p-type. The conductivity type of the doped layer can be the same as or different from that of the silicon substrate, and can be selected according to practical applications. When a p-type silicon substrate is used as the substrate of the solar cell, the elements of the first doping region 2 and the second doping region 3 can be group III elements, such as boron, gallium, etc.; at this time, the silicon substrate and the above-mentioned first doping region The conductivity type of the impurity region 2 and the second doped region 3 are the same, both of which are p-type conductivity. The side of the silicon substrate 1 close to the doped region is used as a surface field, and a corresponding PN junction is formed on the other side of the silicon substrate, which can be used as a surface field. form a complete solar cell. When an n-type silicon substrate is used as the substrate of the solar cell, the elements of the first doping region 2 and the second doping region 3 can be group III elements, such as boron, gallium, etc.; the first doping region 2 and the second doping region 3 The conductivity types of the impurity regions 3 are the same, and they are all p-type conductivity. In this case, a solar cell with good performance can also be formed. Of course, the doping elements of the first doping region 2 and the second doping region 3 may also be Group V elements, such as phosphorus elements; in this case, the silicon substrate and the above-mentioned first doping region 2 and second doping region 3 The conductivity type is the same, both are n-type conductivity, the doped surface is used as a surface field, and a corresponding PN junction is formed on the other side of the cell, and a solar cell with good performance can still be obtained.

In this embodiment, the first doped region 2 and the plurality of second doped regions 3 may be on the same plane. This embodiment does not limit the setting forms of the two. The areas occupied by the first doped region 2 and the second doped region 3 may be the same or different, and are determined according to specific conditions. The electrode device can penetrate the passivation film and make contact with both the first doped region 2 and the second doped region 3 .

It can be clearly concluded from the above that, in the solar cell structure provided by the present invention, by arranging the second doping region 3 with a higher doping concentration in the doping layer, the concentration of carriers is greatly improved, and the second doping region is also greatly improved. The resistivity of 3 decreases, thus increasing the current collection capability. At the same time, the distance between the metal electrodes in the electrode device can be increased to reduce the contact area between the metal electrode and the doped layer. Since the area ratio of the metal electrode is relatively reduced, the contact area between the metal electrode and the doped layer is reduced, thereby reducing the metal electrode. The carrier recombination rate in the contact area with the semiconductor ultimately improves the efficiency of the cell.

Referring to FIGS. 1-2 and 8-9 , in the above embodiment, each of the second doping regions 3 is distributed in the first doping region 2 at intervals.

Specifically, the first doped regions 2 and the second doped regions 3 may both be strip-shaped structures, and the number of the second doped regions 3 may be determined according to actual conditions. A plurality of second doping regions 3 can be arranged in the first doping region 2 at equal intervals, and at the same time the first doping region 2 is divided into a plurality of first doping sub-regions, each first doping sub-region and each The second doped regions 3 are separated from each other in an alternating manner.

Although the high-concentration doped region has high conductivity, the carrier recombination is serious, therefore, preferably, the width of each of the second doped regions 3 is smaller than that between any two of the second doped regions 3 , that is, the width of each of the second doped regions 3 is smaller than the width of each of the first doped sub-regions.

Specifically, the width of each first doped sub-region can be determined according to the width of any two adjacent second doped regions 3 . In specific implementation, the width of each second doped region 3 may be 20-300 μm, preferably 100-250 μm, and more preferably 200 μm, according to which the width of each first doped sub-region can be determined. For example, in this embodiment, the width of each second doped region 3 is 20 μm, 100 μm, 200 μm, 300 μm, and the like. The spacing between any two adjacent second doped regions 3 is 300-2000 μm, preferably 600-1200 μm, and more preferably 800-1000 μm. For example, in this embodiment, the distance between any two adjacent second doped regions 3 may be 300 μm, 800 μm, 1000 μm, 1200 μm, or the like.

In the above-mentioned embodiments, the electrode grid lines in the electrode device are arranged at an included angle with the second doped region 3 . That is to say, the electrode grid lines can be arranged to intersect with the second doped region 3 at any angle, but in order to ensure good carrier transfer, preferably, the electrode grid lines in the electrode device and the second doped region 3 3 vertical settings. Obviously, the electrode grid lines in the electrode device are also arranged at an angle with the first doped region 2 . Preferably, the electrode grid lines in the electrode device are arranged perpendicular to the first doped region 2 .

Referring to FIG. 7 again, in the above-mentioned embodiment, on the first doped region 2, a plurality of the second doped regions 3 are arranged at intervals along the length direction of the electrode grid lines in the electrode device, and are located in different electrode grids. The corresponding two second doped regions 3 below the line are spaced apart from each other to optimize the path of current collection. Wherein, the second-type doped regions 3 separated from each other are all in contact with the electrode gate lines.

In this embodiment, preferably, the second doped regions 3 located under different electrode grid lines are arranged at equal intervals, so that the current collection of each doped region is relatively uniform. Further preferably, the second doped regions 3 located under the same electrode grid line are arranged at equal intervals, so that the current collection of each doped region is more uniform.

Specifically, the regions where both ends of the first doped region 2 are in contact with the electrode grid lines may have a dentate structure, and each second doped region 3 may be embedded in the first doped region 2 between every two dentate structures. in the gap between. The distance between the corresponding two second doped regions 3 located under different electrode grid lines can be determined according to the actual situation. In actual design, it is embedded between the first doped regions 3 along the length direction of the electrode grid lines. Each of the second doped regions 3 in the void is in contact with the electrode device.

In the above embodiments, in order to optimize the concentration distribution of the doping elements on the surface of the battery, each second doping region 3 is a strip-shaped structure, and each second doping region 3 is in contact with at least a section of the electrode grid line.

Specifically, since the electrode grid lines may be in a linear shape or a block shape, each second doped region 3 may be in contact with one or more segments of the electrode grid lines. Obviously, the first doped region 2 can also be in contact with one or more sections of electrode grid lines.

Continuing to refer to FIGS. 7-9, in the above embodiments, when the doping layer is located on the front side of the silicon substrate, and the back side of the silicon substrate is in contact with the back electrode through the back passivation film opening region 8, a single-sided solar cell can be formed. or bifacial solar cells.

Specifically, the back electrode includes an aluminum-containing electrode 9 and a positive electrode connection electrode 10 . The aluminum-containing electrode 9 can be a sheet-like structure, which completely covers the area where the backside passivation film is located, and makes the aluminum-containing electrode 9 penetrate the backside passivation film and contact the silicon substrate, and what is formed at this time is a single-sided solar cell ( as shown in Figure 9). The aluminum-containing electrode 9 can also be a strip-shaped structure, which is arranged at intervals in the open-film region 8 of the passivation film on the backside. At this time, a double-sided solar cell is formed (as shown in FIG. 7 and FIG. 8 ).

It can be seen that, because the second doping region 3 has a higher doping concentration, the electrical conductivity of the surface of the solar cell emitter is enhanced, thereby helping to improve the current collection capability of the electrode device. The efficiency of the solar cell prepared by the solar cell structure has also been greatly improved.

To sum up, in the solar cell structure provided by the present invention, by setting a second doping region with a higher doping concentration in the doping layer, the concentration of carriers is greatly improved, and the resistance of the second doping region is also increased. rate decreases, thus increasing the current collection capacity. At the same time, the distance between the metal electrodes in the electrode device can be increased to reduce the contact area between the metal electrode and the doped layer. Since the area ratio of the metal electrode is relatively reduced, the contact area between the metal electrode and the doped layer is reduced, thereby reducing the metal electrode. The carrier recombination rate in the contact area with the semiconductor, and due to the reduction of the metal area ratio, can also greatly reduce the shading problem caused by the metal, improve the light utilization rate of the solar cell, and ultimately improve the efficiency of the cell.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit and scope of the invention. Thus, provided that these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims (13)

1. A solar cell structure, comprising: the silicon substrate, the doping layer, the passivation film layer and the electrode device are sequentially arranged from the silicon substrate to the outside;

the doping layer comprises a first doping region and a plurality of second doping regions, and the first doping region and the second doping regions have the same conductivity type; the doping concentration of the second doping region is higher than that of the first doping region; the electrode device is in contact with both the first doped region and the second doped region.

2. The solar cell structure of claim 1, wherein each of the second doped regions is spaced apart in the first doped region.

3. The solar cell structure of claim 2, wherein the width of each second doped region is smaller than the distance between any two adjacent second doped regions.

4. The solar cell structure of claim 3, wherein the width of each of the second doped regions is 20-300 μm; the distance between the second doping regions is 300-2000 μm.

5. The solar cell structure according to claim 1, wherein a plurality of the second doping regions are respectively disposed at intervals along a length direction of an electrode grid line in the electrode device on the first doping region, and two corresponding second doping regions located below different electrode grid lines are spaced from each other.

6. The solar cell structure of claim 5, wherein the second doped regions under different grid lines of the electrode are equally spaced.

7. The solar cell structure of claim 5, wherein the second doped regions are disposed at equal intervals under the same electrode grid line.

8. The solar cell structure according to any one of claims 1 to 7, wherein the electrode gridlines in the electrode device are disposed at an angle to the second doped region.

9. The solar cell structure of claim 8, wherein the electrode gridlines in the electrode device are disposed perpendicular to the second doped region.

10. The solar cell structure according to any one of claims 1 to 7, wherein the second doped regions are stripe structures, and each of the second doped regions is in contact with at least one segment of the electrode grid line.

11. The solar cell structure according to any of claims 1 to 7, wherein the doping concentration of the first doped region is 5 × 10¹⁸～5×10²⁰Per cm³The doping concentration of the second doping region is 1 × 10¹⁹～5×10²¹Per cm³。

12. The solar cell structure according to any one of claims 1 to 7, wherein the pitch between every two electrode grid lines in the electrode device is 1-4 mm.

13. The solar cell structure according to any one of claims 1 to 7, wherein the passivation film layer is composed of one or more of silicon nitride, silicon oxide, silicon oxynitride, aluminum oxide, and silicon carbide.

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