JP2010103572A - Method for manufacturing solar cell element, and solar cell element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a solar cell element which reduces irregularities of the surface of a collector electrode formed in a screen printing process step to reduce its resistance value, and contributes to improvement in photoelectric conversion performance. <P>SOLUTION: When the collector electrode 5 of the solar cell element is formed (d) by conductive paste screen printing, screen printing treatment is repeated two or more times. At this moment, each screen printing treatment is executed using a different mesh pattern. By repeating screen printing treatment plural times, the surface of the collector electrode 5 formed is flattened. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a solar cell element and a solar cell element.

  FIG. 5 is a cross-sectional view showing the structure of a solar cell element having a pin junction using a crystalline semiconductor and an amorphous semiconductor. In FIG. 5, reference numeral 1 denotes an n-type crystalline silicon substrate made of a crystalline semiconductor such as single crystal silicon or polycrystalline silicon. On one main surface of the crystalline silicon substrate 1, an i-type amorphous silicon layer 2 and a p-type amorphous silicon layer 3 are laminated in this order, and a light transmitting material made of, for example, ITO is further formed thereon. Comb-shaped collector electrode 5 made of conductive conductive film 4 and Ag is formed. On the other main surface of the crystalline silicon substrate 1, an i-type amorphous silicon layer 6 and an n-type amorphous silicon layer 7 are laminated in this order. Comb-shaped collector electrode 9 made of conductive conductive film 8 and Ag is formed.

  Such a solar cell element is manufactured by the following procedure. First, an i-type amorphous silicon layer 2 and a p-type amorphous silicon layer 3 are continuously formed on one main surface of the crystalline silicon substrate 1 using a plasma CVD method, An i-type amorphous silicon layer 6 and an n-type amorphous silicon layer 7 are continuously formed on the main surface. Next, a light-transmitting conductive film 4 and a light-transmitting conductive film 8 are formed on the amorphous silicon layer 3 and the amorphous silicon layer 7 by a sputtering method, and further, a light-transmitting film is formed by a screen printing method. Comb-shaped collector electrode 5 and collector electrode 9 are formed on conductive conductive film 4 and translucent conductive film 8.

  In the solar cell element having such a structure, each layer other than the crystalline silicon substrate 1 can be formed at a temperature of 200 ° C. or lower using a method such as plasma CVD, sputtering, or screen printing. Further, it is possible to prevent the substrate from warping and to reduce the manufacturing cost. Since the solar cell element having such a structure is manufactured in a low temperature environment in order to suppress thermal damage to the amorphous silicon layers 2, 3, 6, 7, the Ag paste for the collector electrodes 5, 9 is used. Also, pastes for low temperature and drying are used, and thus the resistance value is high.

  FIG. 6 is a schematic diagram showing a screen printing process of a conductive paste (Ag paste) used in the above-described method for manufacturing a solar cell element, and FIG. 6 (a) shows the middle of the processing process. (B) shows the shape of the electrode after it is finished. Emulsion 11 and mesh 12 are integrated, and screen mesh 17 lacking emulsion 11 corresponding to the part where the electrode is to be formed is placed on base 13, and squeegee 14 is moved to place conductive paste 15 on base 13 The electrode 16 having a predetermined width is formed by coating.

  In such a screen printing process, the thickness of 40 μm is the limit with respect to the line width of 120 μm in one printing process, and there are many variations. Further, as shown in FIG. 6B, the unevenness of the electrode 16 due to the pattern shape of the mesh 12 is large. Due to such a cause, the resistance becomes high, the loss of current is large, and the improvement of the photoelectric conversion characteristics is hindered.

  The present invention has been made in view of such circumstances, and it is possible to reduce the unevenness of the surface of the electrode formed in the screen printing process to reduce its resistance value, and to improve the photoelectric conversion characteristics. It aims at providing the manufacturing method of a solar cell element which can contribute, and a solar cell element.

  Another object of the present invention is to provide a method of manufacturing a solar cell element and a solar cell element in which a tab can be easily attached to a collector electrode and the adhesion between the collector electrode and a lead wire is good.

  The method for manufacturing a solar cell element according to claim 1 is a method for manufacturing a solar cell element including a step of screen-printing a conductive paste to form a collecting electrode, and repeating the screen printing process of the conductive paste a plurality of times. It is characterized by.

  According to a second aspect of the present invention, there is provided a method for manufacturing a solar cell element according to the first aspect, wherein the screen mesh pattern is changed for each of the plurality of screen printing processes.

  The method for producing a solar cell element according to claim 3 is characterized in that, in claim 1 or 2, the conductive paste contains Ag as a main component.

  The method for producing a solar cell element according to claim 4 is the method according to any one of claims 1 to 3, wherein in the plurality of screen printing processes, the first screen printing process and the second and subsequent screen printing processes are electrically conductive. The paste material is different, and the conductive paste material in the second and subsequent screen printing processes has better connectivity with the solder than the conductive paste material in the first screen printing process. And

  According to a fifth aspect of the present invention, there is provided a solar cell element comprising a collector electrode formed by a plurality of screen printing processes of a conductive paste.

  In the present invention, the screen printing process is repeated a plurality of times when the collector electrode is formed. Thereby, the unevenness | corrugation of the surface of the formed collector electrode is reduced, and planarization is attained. At this time, the screen printing process is performed each time using different mesh patterns. Thereby, further planarization of the collector electrode surface is realizable. By reducing the unevenness on the surface, it is possible to prevent the resistance of the collector electrode from increasing even if a high-resistance conductive paste used in a low-temperature environment is used, and to improve photoelectric conversion characteristics, particularly F.F. (curve factor). Further, since the surface of the collecting electrode is flat, it is possible to easily attach a tab in a later process.

  In the present invention, in the second and subsequent screen printing processes, a conductive paste made of a material having better solderability than the first screen printing process is used. In this case, since the surface of the collector electrode to be formed is made of a material having good connectivity with the solder, the tab can be easily attached and the adhesion of the lead wire for current extraction can be improved.

  As described above, in the method for manufacturing a solar cell element of the present invention, since the collector electrode is formed by repeating the screen printing process of the conductive paste twice or more, the surface of the collector electrode due to the pattern of the screen mesh is formed. Unevenness can be reduced, the resistance of the collector electrode can be reduced, and the photoelectric conversion characteristics can be improved. At this time, if a screen mesh having a different pattern is used in each printing process, a greater effect can be obtained.

It is sectional drawing which shows the process of the manufacturing method of the solar cell element of this invention. It is a figure which shows the screen mesh used by the screen printing process of the 1st time of this invention, and the shape of the electrode formed when it is used. It is a figure which shows the screen mesh used by the screen printing process of the 2nd time of this invention, and the shape of the electrode formed when it is used. It is a figure which shows the shape of the collector electrode formed by this invention. It is sectional drawing of a solar cell element. It is a schematic diagram which shows the conventional screen printing process.

  Hereinafter, the present invention will be described in detail with reference to the drawings showing embodiments thereof. FIG. 1 is a cross-sectional view showing steps of a method for manufacturing a solar cell element of the present invention.

First, an i-type amorphous silicon layer 2 is formed on one main surface of an n-type crystalline silicon substrate 1 by a plasma CVD method using SiH ₄ , and then SiH ₄ and B are formed thereon. _A p-type amorphous silicon layer 3 is formed by a plasma CVD method using a mixed gas with ₂ H ₆ (FIG. 1A). Further, an i-type amorphous silicon layer 6 is formed on the other main surface of the crystalline silicon substrate 1 by a plasma CVD method using SiH ₄ , and then SiH ₄ and PH ₃ are formed thereon. An n-type amorphous silicon layer 7 is formed by plasma CVD using a mixed gas (FIG. 1B).

  Next, a light-transmitting conductive film 4 and a light-transmitting conductive film 8 each made of ITO are formed on the amorphous silicon layer 3 and the amorphous silicon layer 7 by sputtering, respectively (see FIG. 1 (c)). Finally, the collector electrode 5 and the collector electrode 9 are formed on the translucent conductive film 4 and the translucent conductive film 8 by screen printing using Ag paste, respectively (FIG. 1D). .

  In the present invention, when the collector electrode 5 is formed by the screen printing method using Ag paste in the above-described steps, the printing process is repeated twice by changing the screen mesh pattern. 2 and 3 are diagrams showing two types of screen meshes having different patterns used in the present invention and the shapes of electrodes formed using the screen meshes. 2A and 2B show the screen mesh A used for the first printing process and the shape of the electrode after printing when the screen mesh A is used, and FIGS. 3A and 3B show the second time. The screen mesh B used for the printing process and the shape of the electrode after printing when using it are shown. In the portion where the electrode is formed, the peak positions of the horizontal lines of the screen meshes A and B are shifted, and the uneven shape of the formed electrode is also different.

  In the present invention, the screen mesh A as shown in FIG. 2 is used in the first printing process, and the screen mesh B as shown in FIG. 3 is used in the second printing process. Table 1 below shows experimental results of thickness variation after the end of each printing process when the collector electrode 5 having a line width of 0.12 mm is formed in this manner.

  From the results of Table 1, it can be seen that the unevenness of the formed electrodes can be reduced by performing overprinting using the screen meshes A and B having two different patterns in this way. This is because the unevenness caused by the patterns of the screen meshes A and B was offset by overprinting, and the Ag paste was highly viscous and the printing process was repeated twice. Due to and.

  As described above, by repeating the printing process twice with different mesh patterns, the planarized collector electrode 5 can be formed with reduced surface irregularities, as shown in FIG.

Next, the characteristics of the solar cell element manufactured as described above will be described. First, the resistance value of the collector electrode 5 could be reduced by 25% compared with the solar cell element manufactured by the conventional method (one screen printing) according to the reduction | decrease in the unevenness | corrugation of the surface. Further, FF, which is one of photoelectric conversion characteristics, was 0.75, which was 7.1% compared to 0.70 in the conventional example, which was improved by 7.1%. Furthermore, as a result of examining the output of a 103 mm square solar cell in which a large number of these solar cell elements were connected in series, it was confirmed that the solar cell element was improved by 6% as compared with the conventional example.

  In the above example, a screen mesh having a different pattern was used, but when the printing process was repeated twice using the same screen mesh, the resistance value could be reduced by 20% compared to the conventional example, FF also improved by 6.3%.

  Further, when Cu paste or Al paste was used instead of the above Ag paste as the conductive paste to be used, the same characteristics as in the case of Ag paste were obtained.

  In the above example, the same type of conductive paste is used in the two screen printing steps, but different types of conductive paste may be used. In such a case, if the Ag paste is used for the first time and the Cu paste, Cr paste or the like having better solderability than this Ag paste is used for the second time, tabs can be formed in the subsequent process. There is an advantage that it is easy to attach to the collector electrode 5, and it is difficult to remove the tab from the collector electrode 5, and the solar cell element can be easily handled in a later process.

1 Crystalline silicon substrate 2,6 Amorphous silicon layer (i-type)
3 Amorphous silicon layer (p-type)
4,8 Translucent conductive film 5,9 Collector 7 Amorphous silicon layer (n-type)
A, B Screen mesh

Claims (3)

A method for producing a solar cell element comprising a crystalline silicon substrate and having a collector electrode on the surface,
The method of manufacturing a solar cell element, wherein the collector electrode is formed by multiple printing of a conductive paste at a collector electrode forming position.   In the multiple overprinting of the conductive paste, the material of the conductive paste used for the first time is different from the material of the conductive paste used for the second time, and is used for the second time compared to the material of the conductive paste used for the first time. The method for manufacturing a solar cell element according to claim 1, wherein the material of the conductive paste has good connectivity with solder. A solar cell element comprising a crystalline silicon substrate and having a collector electrode formed on the surface,
The solar cell element, wherein the collector electrode is formed by overprinting a conductive paste at a collector electrode forming position a plurality of times.

Images