CN105405901B - Localized contact back of the body passivation solar cell - Google Patents

Abstract

The invention discloses a partial contact back passivation solar cell, which comprises a silicon substrate layer, a back passivation film located on the bottom surface of the silicon substrate layer, a back metal layer covering the bottom surface of the back passivation film, and a back passivation film which runs through the back passivation film and the back surface. A plurality of back silver electrodes in the metal layer and in contact with the bottom surface of the silicon substrate layer, a plurality of contact regions penetrating the back passivation film; and sub-gate electrodes parallel to each other on the front side of the silicon substrate layer; the contact region is in the shape of a line segment and Arranged in multiple rows parallel to each other, the contact areas in each row are parallel to each other and distributed at intervals, and the contact areas in adjacent rows are staggered; in each row of contact areas, the length of each contact area is 0.1~0.9mm; adjacent The distance c between two rows of contact regions is 0.5-1mm; the total area of the contact regions accounts for 1-3.5% of the area of the backside of the silicon wafer. Experiments prove that: compared with the prior art, the photoelectric conversion efficiency of the present invention is increased by 0.43-0.46%, and unexpected technical effects have been achieved.

Description

Local Contact Back Passivation Solar Cells

technical field

The invention relates to a partial contact back passivation solar cell, which belongs to the technical field of solar cells.

Background technique

Conventional fossil fuels are being exhausted day by day. Among the existing sustainable energy sources, solar energy is undoubtedly the cleanest, most common and most potential alternative energy source. Solar power generation devices, also known as solar cells or photovoltaic cells, can directly convert solar energy into electrical energy. The principle of power generation is based on the photovoltaic effect of semiconductor PN junctions.

With the development of science and technology, a partial contact back passivation solar cell has appeared, which is a newly developed high-efficiency solar cell and has received extensive attention from the industry. Its core is to cover the backlight surface of the silicon wafer with an aluminum oxide or silicon oxide film (also known as the back passivation film, generally with a thickness of 5 to 100 nanometers) to passivate the surface and improve the long-wave response, thereby improving the performance of the battery. conversion efficiency. However, aluminum oxide or silicon oxide is not conductive, so the film needs to be partially opened so that the back metal layer (such as aluminum metal) can contact the back surface of the silicon wafer to collect current.

At present, the contact patterns (that is, the metallization method) between the metal on the back side of the local contact back passivation solar cell and the silicon substrate used to collect current mainly include triangular circular holes and continuous and parallel lines. However, these two metallization methods have their own shortcomings: 1. The circular hole design is prone to produce voids in the contact area, which increases the contact resistance and reduces the battery efficiency; 2. The continuous line leads to the contact area between metal and silicon. Larger, resulting in a decrease in the passivation area, on the one hand, it is not conducive to passivation, on the other hand, it leads to more serious surface recombination, which also reduces the battery efficiency.

In view of the above problems, Chinese utility model patent CN203932078U discloses a back passivated solar cell, comprising a silicon substrate layer, an emitter layer formed on the upper surface of the silicon substrate layer, an anti-reflection film layer located on the upper surface of the emitter layer, penetrating through A plurality of front silver electrodes in the anti-reflection film layer and in contact with the upper surface of the emitter layer, a back passivation film located on the bottom surface of the silicon substrate layer, a back metal layer covering the bottom surface of the back passivation film, penetrating through the back passivation film and a plurality of back silver electrodes in the back metal layer that are in contact with the bottom surface of the silicon substrate layer, and a plurality of contact areas that run through the back passivation film, the upper surface of the contact area is in contact with the bottom surface of the silicon substrate layer, and the contact area is in the form of The shape of the line segment is arranged in multiple rows parallel to each other, the contact areas in each row are parallel to each other and distributed at intervals, and the contact areas in adjacent rows are distributed alternately. Its dependent claim 8 records: the length of the contact area is 1-5 mm, and the width is 20-80 microns.

Therefore, it is always a research and development method for those skilled in the art to develop local contact back passivated solar cells with high conversion efficiency.

Contents of the invention

The object of the present invention is to provide a partial contact back passivation solar cell.

In order to achieve the above-mentioned purpose of the invention, the technical solution adopted in the present invention is: a kind of partial contact back passivation solar cell, comprising silicon substrate layer, the back passivation film positioned at the bottom surface of the silicon substrate layer, the back metal covering the bottom surface of the back passivation film layer, a plurality of back silver electrodes penetrating through the back passivation film and the back metal layer and in contact with the bottom surface of the silicon substrate layer, a plurality of contact regions penetrating the back passivation film; and auxiliary gates parallel to each other on the front side of the silicon substrate layer electrode;

The upper surface of the contact area is in contact with the bottom surface of the silicon substrate layer, the contact area is in the shape of a line segment and arranged in multiple rows parallel to each other, the contact areas in each row are parallel to each other and distributed at intervals, and the contact areas in adjacent rows are staggered distributed;

In each row of contact areas, the length of each contact area is a, and the distance between adjacent contact areas is b; and a is 0.1~0.9 mm; b is: 0.5a≤b≤3a;

The distance c between two adjacent rows of contact areas is 0.5~1 mm;

The total area of the contact area accounts for 1-3.5% of the area of the backside of the silicon wafer.

Preferably, the distances between two adjacent rows of contact regions are the same.

In the above technical solution, the width of the contact area is 20-80 microns.

In the above technical solution, the extension direction of the contact region is parallel to the extension direction of the front sub-gate electrode.

Preferably, the total area of the contact area accounts for 1.5-3% of the area of the back surface of the silicon wafer.

In the above technical solution, the contact region is in contact with or embedded in the back metal layer.

In the above technical solution, the back metal layer is an aluminum layer, and the contact area is a silicon aluminum alloy contact area.

Preferably, the back metal layer is an aluminum layer, and the material of the contact area is silver.

In the above technical solution, the contact region penetrates through the back metal layer.

A back field layer is formed between the back passivation film and the silicon substrate layer, the back silver electrode is in contact with the bottom surface of the back field layer, and the upper surface of the contact area is in contact with the bottom surface of the back field layer.

Due to the use of the above-mentioned technical solutions, the present invention has the following advantages compared with the prior art:

1. The present invention has developed a new local contact back passivation solar cell structure, by strictly controlling the length of each contact area, the spacing between adjacent contact areas in a row, the spacing between two adjacent row contact areas, and The ratio of the total area of the contact area to the area on the back of the silicon wafer finally results in a solar cell with superior performance; experiments have proved that compared with the prior art, the present invention can significantly reduce the proportion of silicon-aluminum holes, and the open circuit voltage is increased by 0.002~0.004 V, the short-circuit current increased by 0.08~0.12A, and the photoelectric conversion efficiency increased by 0.43~0.46%, achieving unexpected technical effects;

2. In the present invention, the extension direction of the contact area is perpendicular to the extension direction of the back silver electrode, which greatly reduces the current collection path, is beneficial to reduce the series resistance, and improves the photoelectric conversion efficiency of the battery, achieving remarkable results;

3. The structure of the present invention is simple, the cost is low, and it is suitable for popularization and application.

Description of drawings

Fig. 1 is a sectional view of Embodiment 1 of the present invention.

Fig. 2 is a schematic view of the back of Embodiment 1 of the present invention.

FIG. 3 is a partially enlarged view of a part of the contact area in FIG. 2 .

Fig. 4 is a schematic view of the back side of Embodiment 2 of the present invention.

Fig. 5 is a schematic view of the back of Comparative Example 1 of the present invention.

Among them: 1. Silicon substrate layer; 2. Passivation film on the back side; 3. Metal layer on the back side; 4. Silver electrode on the back side; 5. Contact area.

Detailed ways

The present invention is further described below in conjunction with embodiment.

Embodiment one:

Referring to Figures 1 to 3, a partially contacted back passivated solar cell comprises a silicon substrate layer 1, a back passivation film 2 located on the bottom of the silicon substrate layer, a back metal layer 3 covering the bottom of the back passivation film, a through A plurality of back silver electrodes 4 in the back passivation film and the back metal layer and in contact with the bottom surface of the silicon substrate layer, and a plurality of contact regions 5 penetrating the back passivation film;

The upper surface of the contact area is in contact with the bottom surface of the silicon substrate layer, the contact area is in the shape of a line segment and arranged in multiple rows parallel to each other, the contact areas in each row are parallel to each other and distributed at intervals, and the contact areas in adjacent rows are staggered distributed;

In each row of contact areas, the length of each contact area is a, and the distance between adjacent contact areas is b; and a is 0.6 mm; b is 0.9 mm;

The spacing c between two adjacent rows of contact areas is 0.9 mm; the spacing between adjacent two rows of contact areas is the same;

The total area of the contact area accounts for 1.8% of the area of the backside of the silicon wafer.

In the above technical solution, the width of the contact area is 40 microns.

The extending direction of the contact area is perpendicular to the extending direction of the back silver electrode.

The back metal layer is an aluminum layer, and the contact area is a silicon aluminum alloy contact area.

Embodiment two:

Referring to Fig. 4, a kind of local contact back passivation solar cell, its structure is similar to that of Embodiment 1, the difference is:

In each row of contact areas, the length of each contact area is a, and the distance between adjacent contact areas is b; and a is 0.6 mm; b=a, 0.6 mm;

The spacing c between two adjacent rows of contact areas is 0.8 mm; the spacing between adjacent two rows of contact areas is the same;

The total area of the contact area accounts for 2.5% of the area of the backside of the silicon wafer.

In the above technical solution, the width of the contact area is 30 microns.

The extension direction of the contact area is the same as the extension direction of the back silver electrode.

The back metal layer is an aluminum layer, and the contact area is a silicon aluminum alloy contact area.

Comparative example one:

Referring to Fig. 5, a kind of partial contact back passivation solar cell, its structure is myopic with embodiment two, the difference is:

In each row of contact areas, the length of each contact area is a, and the distance between adjacent contact areas is b; and a is 2 mm; b is 2.4 mm;

The spacing c between two adjacent rows of contact areas is 2.6 mm; the spacing between adjacent two rows of contact areas is the same;

The total area of the contact area accounts for 1.0% of the area of the backside of the silicon wafer.

In the above technical solution, the width of the contact area is 60 microns.

The extension direction of the contact area is the same as the extension direction of the back silver electrode.

Comparative example two:

A kind of local contact back passivation solar cell, its structure is different from that of comparative example 1 in that:

In each row of contact areas, the length of each contact area is a, and the distance between adjacent contact areas is b; and a is 4 mm; b is 1 mm;

The spacing c between two adjacent rows of contact areas is 1.0 mm; the spacing between adjacent two rows of contact areas is the same;

The total area of the contact area accounts for 4% of the area of the backside of the silicon wafer.

In the above technical solution, the width of the contact area is 50 microns.

The extension direction of the contact area is the same as the extension direction of the back silver electrode.

Then, the cells of 60 embodiments and comparative examples are made into solar cell modules, and the electrical performance test is carried out, and the results are as follows:

It can be seen from the above table that compared with Comparative Example 1, the present invention can significantly reduce the proportion of silicon-aluminum pores, increase the open circuit voltage by 0.002~0.004V, increase the short circuit current by 0.08~0.12A, and increase the photoelectric conversion efficiency by 0.43~0.46% , achieved unexpected technical effects.

Claims (8)

1. A local contact back passivation solar cell, comprising a silicon substrate layer (1), a back passivation film (2) positioned at the bottom surface of the silicon substrate layer, a back metal layer (3) covering the bottom surface of the back passivation film, through A plurality of back silver electrodes (4) in the back passivation film and the back metal layer and in contact with the bottom surface of the silicon substrate layer, a plurality of contact regions (5) running through the back passivation film; and parallel to each other on the front side of the silicon substrate layer sub-gate electrode; The upper surface of the contact area is in contact with the bottom surface of the silicon substrate layer, the contact area is in the shape of a line segment and arranged in multiple rows parallel to each other, the contact areas in each horizontal row are parallel to each other and distributed at intervals, and the contact areas in adjacent rows are staggered Distribution, the extension direction of the contact area is perpendicular to the extension direction of the back silver electrode; it is characterized in that: In each wale contact area, the length of each contact area is a, and the distance between adjacent contact areas in each wale is b; and a is 0.6~0.9mm; b is: 0.5a≤b≤3a; The distance c between two adjacent longitudinal contact areas is 0.5~1mm; The total area of the contact area accounts for 1-3.5% of the area of the backside of the silicon wafer. 2 . The partial contact back passivated solar cell according to claim 1 , wherein the distances between two adjacent rows of contact regions are the same. 3. The solar cell with partial contact back passivation according to claim 1, characterized in that: the width of the contact area is 20-80 microns. 4 . The partially contacted rear passivated solar cell according to claim 1 , wherein the extension direction of the contact region is parallel to the extension direction of the front sub-gate electrode. 5 . The partial contact back passivated solar cell according to claim 1 , wherein the total area of the contact area accounts for 1.5-3% of the area of the back side of the silicon wafer. 6 . 6 . The partial contact back passivated solar cell according to claim 1 , wherein the contact region is in contact with or embedded in the back metal layer. 7 . 7 . The partial contact back passivated solar cell according to claim 1 , wherein the back metal layer is an aluminum layer, and the contact area is a silicon aluminum alloy contact area. 8 . The partial contact back passivated solar cell according to claim 1 , wherein the contact region penetrates through the back metal layer.