Patent Description:
In an existing manufacturing process of a solar cell, a laser scribing process is usually employed to perform laser cutting processing for a solar cell assembly. The common laser scribing process is mainly divided into three steps, and each step includes one process of structured trenches, which is also referred to as processing line, abbreviated as P1, P2 and P3 processing lines, as shown in <FIG>. The three processing lines are arranged in sequence, and the section from P1 to P3 is a dead zone part of the solar cell, where the P1 processing line is mainly to cut off a front electrode layer A, and process a structured trench by laser beam on the front electrode layer A; the P2 processing line is mainly to cut off a light absorption layer B and process another structured trench by laser beam on the light absorption layer B; the P3 processing line is mainly to cut off a back electrode layer C or the back electrode layer C and the light absorption layer B, and process a third structured trench by laser beam on the back electrode layer C. After P1 cutting processing, the light absorption layer B is prepared and the material of the light absorption layer fills up and covers the P1 processing line. After P2 cutting processing, the back electrode layer C is prepared, and the material of the back electrode layer fills up and covers the P2 processing line. After P3 cutting processing, the surface of the back electrode layer C is not covered with any other covering material, such that the light absorption layer B and the front electrode layer A are directly exposed. The exposed light absorption layer B is directly exposed to air and may easily react with various ingredients of the air to cause effective ingredients to be decomposed, thus further weakening stability of the solar cell and reducing the service life of the solar cell.

In another aspect, an existing cutting process cannot obtain a smooth and flat P3 structured trench. When the existing P3 cutting is performed, it is easy to produce edge collapse and the like at both side edges of the trench, such that the edges of the P3 structured trench is roughened. Further, it is possible that conducive ingredients, such as material scraps and the like, of the back electrode layer fall into the trench after being processed, and thus, the back electrode layer C and the front electrode layer A may be short-circuited due to direct contact, or other substances fall into the trench and react with the material of the light absorption layer, causing the material to be decomposed and so on.

In an existing solution, after P3 laser processing, a protective layer is added to cover the P3 structured trench. This manner requires addition of one procedure, leading to increased costs. Before the protective layer is added, P3 trench is still in an exposed state. Furthermore, the material of the protective layer has difficulty in entering the P3 trench and cannot completely and well cover the P3 trench, producing unstable effect. It is very difficult to achieve the addition of the protective layer.

<CIT> discloses a silicon thin film solar cell with simple packaging, which uses laser etching technology to etch an isolation trench around the periphery of the unit cell, and insulates, resists solder, moisture, acid and alkali in the screen. The back paint layer completely separates the film layer on the outer edge of the battery from the film layer in the effective working area of the battery, effectively preventing the battery edge from short-circuit leakage, and also blocking the unprotected silicon film layer on the outer edge of the battery.

<CIT> discloses a method for manufacturing a film solar battery comprising a first transparent conductive film which is stacked on a translucent insulating substrate, and then patterned, and a photoelectric transfer layer of amorphous silicon is stacked thereon, and it is patterned by laser scribing, and a second transparent conductive film is stacked thereon, and it is patterned by laser scribe, and a cell is connected in series thereby being integrated, and then a translucent insulating film is made thereon, and further a rear reflecting film is stacked thereon.

<CIT> discloses a solar cell cutting and passivation integrated processing method, wherein a material of the protective layer is partially molten due to a localized high temperature generated by the trench cutting laser and infiltrates into the trench.

In order to solve the above technical problems, the present invention provides a solar cell cutting and passivation integrated processing method according to claim <NUM>. At the time of performing laser cutting processing, passivation is performed for a newly-processed trench at the same time, without needing the procedure of covering a protective layer after laser processing, greatly reducing production costs, saving processing time and significantly reducing an exposure time of the back electrode layer after P3 cutting processing. Further, the trench edges after P3 cutting are repaired to improve the morphology of the P3 trench, improve the stability of cell and extending the service life of the cell.

Compared with the prior arts, in the solar cell cutting and passivation integrated processing method in the present invention, when structured cutting is performed for the back electrode layer or the back electrode layer and the light absorption layer simultaneously by laser beam, a molten part of the material of the protective layer due to a localized high temperature generated by laser processing is enabled to flow into a newly-processed structured trench, which is equivalent to saving a procedure in which a protective material is deposited after one back electrode layer is cut, greatly reducing costs and saving production time. Furthermore, the deposition of the protective material at the time of cutting the back electrode layer may guarantee the accuracy of a deposition position so that the protective material can be accurately deposited in the structured trench of the back electrode layer, so as to more completely cover the narrow trench. Further, the filling process is faster, significantly reducing an exposure time of the light absorption layer after laser cutting. Due to presence of the protective material, edge collapses are difficult to occur at both side edges of the structured trench, such that the morphology of the trench can be improved, and the light absorption layer exposed by the trench can be completely wrapped and protected to avoid decomposition. Further, other impurities may be prevented from falling into the trench, avoiding other adverse influence, improving the stability of the cell and extending the service life of the cell.

In order to make the technical problems to be solved, the technical solutions and beneficial effects of the present disclosure clearer and more understandable, the present invention will be further described in combination with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are used only to explain the present invention rather than limit the present invention.

With reference to <FIG>, there are provided preferred embodiments of a solar cell cutting and passivation integrated processing method in the present invention. The solar cell includes a substrate <NUM>, a front electrode layer <NUM>, a light absorption layer <NUM> and a back electrode layer <NUM> from bottom to top in sequence. The substrate <NUM> is disposed at bottom and the back electrode layer <NUM> is disposed at top.

Before laser structured cutting is performed for the back electrode layer <NUM>, a protective layer <NUM> is disposed on a surface of the back electrode layer <NUM>, and then laser structured cutting is performed for the back electrode layer <NUM>, or the back electrode layer <NUM> and the light absorption layer <NUM> simultaneously through the protective layer <NUM> to obtain a corresponding structured trench P3 while the protective layer <NUM> is kept from being cut by laser. A material of the protective layer <NUM> is partially molten due to a localized high temperature generated by the laser processing in a laser structured cutting process and infiltrates into an underlying corresponding structured trench P3.

The laser ray is a focused light beam which has a maximum energy density on a focal plane and relatively low energy density at other positions. By adjusting a focal distance, the back electrode layer <NUM> is placed on a focal plane of the laser beam and has a relatively high laser energy density at this time. An interface of the back electrode layer <NUM> and the protective layer <NUM> and the material of the protective layer <NUM> are not located on the focal plane of the laser beam and have a relatively low laser energy density. When a laser beam (may be green light, ultraviolet light or infrared light) is irradiated down, partial energy is absorbed by the back electrode layer <NUM> such that the back electrode layer <NUM> is molten and partial energy is absorbed by the material of the protective layer <NUM> or the interface of the protective layer <NUM> and the back electrode layer <NUM> to enable the material of the protective layer <NUM> to melt and flow into a structured trench P3 newly cut by laser beam. In this case, the material of the cut-off part of the structured trench P3 is wrapped by the material of the protective layer <NUM> and mixed with the substance of the protective layer <NUM> and then filled into the structured trench P3 to prevent the cut-off structured trench P3 from contacting with other parts of the cell, thus forming trench protection. Since one layer of protective layer <NUM> is pressed on the back electrode layer <NUM>, edge collapse will not easily occur at both side edges of the structured trench P3 during cutting, so as to improve the morphology of the cut-out structured trench P3. After the structured trench P3 is cut, other parts of the material of the protective layer <NUM> may be torn away or remain on the surface of the back electrode layer <NUM>. The laser cutting may be performed under normal pressure or in a vacuum environment.

During cutting, attention may be paid to adjusting to a proper focal distance of laser beam to ensure the back electrode layer <NUM> is located on the focal plane of the laser beam and the material of the protective layer <NUM> is not located on the focal plane. During cutting, partial energy is absorbed by the back electrode layer <NUM> to form a structured trench P3 by melting, and partial energy is reflected and then absorbed by the interface of the material of the protective layer <NUM> and the back electrode layer <NUM>, or the interior of the material of the protective layer <NUM>, such that the material of the protective layer <NUM> melts and automatically flows into the structured trench P3 to form trench protection.

During cutting, light of proper wavelength is to be selected to provide energy of proper magnitude so as to ensure the structured trench P3 can be cut off without damaging P1 and P2. The material of the protective layer <NUM> also should be a material with a proper melting point, to ensure it can melt and flow into the structured trench P3, without causing the circumstances such as vaporization or non-meltability.

The structured trench P3 is a trench newly cut out by laser beam, or a trench cut out by laser beam on the back electrode layer <NUM> and the light absorption layer <NUM> at the same time.

The protective layer <NUM> is placed before the back electrode layer <NUM> is subjected to P3 laser cutting. By coating or deposition, the protective layer <NUM> may be prepared after the back electrode layer <NUM> is prepared. The material of the protective layer <NUM> acts to fully wrap the exposed material of the light absorption layer <NUM>, so as to block direct contact between the material of the light absorption layer and air, and prevent other impurities from falling into the structured trench P3, thus improving the stability of the light absorption layer <NUM>.

The solar cell cutting and passivation integrated processing method further includes: after the laser structured cutting process is completed for the back electrode layer <NUM> or the back electrode layer <NUM> and the light absorption layer <NUM> simultaneously, removing the protective layer <NUM> on the surface of the back electrode layer <NUM>, and retaining the material of the protective layer <NUM> infiltrating into the structured trench P3.

During laser structured cutting, laser ray performs processing for the back electrode layer <NUM> at a side surface where the protection layer <NUM> is located.

During laser structured cutting, laser ray performs processing for the back electrode layer <NUM> at a side surface where the substrate <NUM> is located.

The material of the protective layer <NUM> is an inert material with a melting point below <NUM> and a conductivity below <NUM> -<NUM>/m.

The protective layer <NUM> is a polymer plastic and the like, including silica gel, polydimethylsiloxane, polyphosphazene, polyethylene, polypropylene, and polystyrene etc. The polymer plastic is coated onto the surface of the back electrode layer <NUM> by coating to form a glue film.

A structured trench on the back electrode layer <NUM> of the solar cell is processed using the above solar cell cutting and passivation integrated processing method, as shown in <FIG>.

A structured trench on the back electrode layer <NUM> and the light absorption layer <NUM> of the solar cell is processed using the above solar cell cutting and passivation integrated processing method, as shown in <FIG>.

The solar cell cutting and passivation integrated processing method according to the present invention will be further described below in combination with specific embodiments.

Claim 1:
A solar cell cutting and passivation integrated processing method, a solar cell sequentially comprising a substrate (<NUM>), a front electrode layer (<NUM>), a light absorption layer (<NUM>) and a back electrode layer (<NUM>) from bottom to top, wherein before laser structured cutting is performed for the back electrode layer (<NUM>), a protective layer (<NUM>) is disposed on a surface of the back electrode layer (<NUM>), and then laser structured cutting is performed for the back electrode layer (<NUM>), or the back electrode layer (<NUM>) and the light absorption layer (<NUM>) simultaneously through the protective layer (<NUM>) to obtain a corresponding structured trench (P3), and a material of the protective layer (<NUM>) is partially molten due to a localized high temperature generated by the laser processing in a laser structured cutting process and infiltrates into the underlying corresponding structured trench (P3),
characterized in that
the laser structured cutting is performed while the protective layer (<NUM>) is kept from being cut by laser,
wherein during cutting, the back electrode layer (<NUM>) is located on the focal plane of the laser beam and the material of the protective layer (<NUM>) is not located on the focal plane.