DE102009026300A1 - Manufacturing method and apparatus for producing thin-film solar cells - Google Patents

Abstract

The invention relates to a production method and a production device for producing thin film solar cells, the method comprising a step of attaching a substrate (1) to a heating plate (5) and a step of depositing a film (2) on the substrate (1), wherein during the application step, a buffer layer (3) is arranged between the heating plate (5) and an application surface (12) of the substrate (1), which covers at least a central region (121) of the substrate application surface (12).

Description

The The invention relates to a manufacturing method and a manufacturing apparatus for the production of thin-film solar cells, in particular copper indium gallium selenide thin film solar cells (CIGS thin film solar cells) and monolithic solar cell modules.

Commercially available manufacturing facilities for Production of thin films for solar cells comprise a heating plate on which a substrate is placed. The substrate is vacuumed through suction holes in the heating plate held on the heating plate. After that, on the Substrate thin film layers deposited to the thin-film solar cells or to form the monolithic modules. Part of the CIGS thin film solar cells can be obtained by a chemical bath deposition (CBD) be deposited, for example, a cadmium sulfide buffer layer on a CIGS layer.

One A major problem after the production of thin-film solar cells is the mechanical stability of the substrate. The substrate, usually is made of glass, is susceptible to damage after the CBD process and stops in Particular often standardized load tests, as provided by the Technical Inspection Association (TÜV) are not standing.

It is therefore an object of the present invention, a manufacturing method and a manufacturing apparatus for producing thin-film solar cells or provide modules with improved mechanical stability.

The Task is in this invention by providing a Manufacturing method with the features of claim 1 and a Manufacturing device with the features of claim 14. advantageous embodiments The invention are the subject of the dependent claims.

The Invention is based on the understanding that while the processing of the substrate in the manufacturing process of the thin film solar cells the direct contact of the substrate with the heating plate to small errors to lead can be introduced into the substrate. Such small mistakes can small scratches or cracks in the substrate surface or in the substrate due to unevenness of the substrate or the heating plate is introduced on a very small scale can be. On the other hand, a close contact between the substrate and the Hotplate desired, around during the deposition process for a powerful and controlled heating of the substrate.

The Buffer layer between the heating plate and a mounting surface of the Substrate is placed, the heat transfer from the heating plate ensure to the substrate while a uniform distribution the on the mounting surface acting forces provides unnecessary Avoid stresses that could damage the substrate. In particular the central region of the substrate attachment surface is at risk. Therefore it could sufficient this part of the mounting surface to cover with the buffer layer.

Of the Middle range could to any single consecutive or multiple Areas on the mounting surface which do not border on the edge of the substrate. In other words it will probably not be enough, for example, the buffer layer in the form of a frame cover only a border area of the mounting surface allow. Rather, it is necessary that a central area is covered. This is because, first of all the central region or the central part of the substrate of a stress is suspended while it is attached to the heating plate because there is the largest vacuum pressure or negative pressure occurs. Therefore, damage to the substrate is most likely in this area or in the bulk of the substrate above this Area occur.

Advantageous the central area comprises at least one central area of the Mounting surface of the Substrate. This can be, for example, an area around the geometric Center of the mounting surface be. If the substrate attachment surface has a rectangular shape, For example, the central area may be an area that is the intersection point surrounds the two diagonals of the rectangle.

Even though a central region of the substrate attachment surface is generally a central region the heating plate on which the substrate is mounted corresponds, could this will not be the case if the heating plate has a surface, which are in size and / or differs in shape from the mounting surface of the substrate.

To attaching the substrate to the heating plate, with between them the buffer layer is arranged, the deposition step can be started, one or more thin films deposit. As an example Such thin films, the Part of Copper Indium Gallium Selenide (CIGS) thin-film solar cells are, for For example, a cadmium sulfide (CdS) film deposited on a CIGS film include. The buffer layer itself may comprise fiberglass, for Example in the form of a glass fiber fabric. In addition, the buffer layer is preferably designed to be antistatic.

In a preferred embodiment the buffer layer is disposed between the heating plate and the substrate, covering substantially the entire substrate mounting surface. As opposed to only partially covering the mounting surface, this has the advantage of allowing protection of the entire surface of the substrate. However, it is possible that the buffer layer is perforated for various purposes or includes holes.

In an advantageous embodiment which is arranged between the heating plate and the substrate Buffer layer of a flexible material. In addition to that it has better Has buffering properties, this feature allows easy application and removal the buffer layer, since this can be rolled or folded. Furthermore can store or supply the buffer layer on a Supply cylinders are kept.

In a preferred embodiment which is arranged between the heating plate and the substrate Buffer layer of a plastic material. The composition of the plastic can according to the required properties be tuned, for example, to the thermal conductivity of the buffer layer too increase. The buffer layer may comprise polytetrafluoroethylene (PTFE).

In an advantageous embodiment which is arranged between the heating plate and the substrate Buffer layer of a fiber material and / or composite materials. The fibrous material, which is a cellulosic material such as a paper sheet has the advantage that a vacuum suction effect through the buffer layer can be exercised without in the layer of holes must be provided. A composite material may be, for example, a glass fiber reinforced polytetrafluoroethylene (PTFE) layer or foil.

In a preferred embodiment has the buffer layer disposed between the heating plate and the substrate a thickness of less than about 1 mm, preferably less than about 0.4 mm and more preferably less than about 0.15 mm. Thin buffer layers have the advantage of providing better heat transfer between the heating plate and the substrate is allowed. Advantageous buffer layer thicknesses can about 0.07 mm, about 0.25 mm or about 0.35 mm.

In an advantageous embodiment the attaching step comprises providing a suction effect through suction holes in the hot plate to the substrate by a vacuum on the hot plate to keep. Holding the substrate by means of a vacuum the heating plate has the advantage that, in contrast to the example a very attaching to other means such as braces even holding pressure exerted on the substrate can be.

In a preferred embodiment the attaching step comprises a step of aligning holes which are provided in the buffer layer, with the suction holes in the heating plate. Such holes could in a regular or be provided in a random pattern.

In an advantageous embodiment is the vacuum pressure for holding the substrate on the hot plate set to between about 10 mbar and about 800 mbar. The vacuum pressure can be dependent on the size and of Weight of the substrate and the size of the Heizplattenfläche set become.

In a preferred embodiment the substrate becomes during the deposition of the film on the substrate to a temperature of more than about 40 ° C, advantageously greater than about 50 ° C and more preferably heated above about 60 ° C. In general, will a temperature of between about 40 ° C and about 90 ° C is preferred. The buffer layer must be made of a material that has a sufficient heat resistance having. The heat resistance should be up to 100 ° C or above be.

In an advantageous embodiment the deposition of the film on the substrate by a chemical Badabscheidung (CBD) performed. For this reason, the substrate can either be in a chemical bath be immersed, or it may alternatively on the substrate surface a liquid Layer of the chemical bath to be set up.

In a preferred embodiment the buffer layer is manually or automatically on the heating plate arranged. For example, the buffer layer may be moved by moving of a cylinder, on which it is wound, over the heating plate on the Heating plate to be rolled before the substrate is positioned. Alternatively, the hot plate may be under a stretched arc of the buffer layer to be moved. If successively several substrates on the heating plate can be arranged, the automatic or manual arrangement of the buffer layer before placing each substrate on the hot plate or it can be a single buffer layer for multiple Substrates are used and only exchanged after she was damaged or if it is likely to get damaged.

In an advantageous embodiment, the buffer layer comprises a self-adhesive surface, which is placed on the heating plate during attachment of the substrate. Alternatively, an adhesive layer can be arranged between the buffer layer and the heating plate. Both cases have the advantage that the buffer layer will not move while the substrate is placed thereon. Self-tackiness may be limited to areas or locations of the buffer layer. For example, a marginal area and / or a central or central area of the buffer layer may be the only part that is covered with an adhesive.

In The following description will be made with reference to the attached schematic drawings some examples of embodiments of the invention in more detail be described, wherein

1a to 1d schematically show the setting up and the deposition of a film for producing thin-film solar cells; and

2 shows an arrangement for thin-film solar cell production, wherein a substrate is arranged on a heating plate.

1a to 1d show in a series of schematic drawings the arrangement for depositing a thin film on a substrate. In 1a is a hot plate 5 shown a heating element 55 includes, which is indicated here as a resistance heating element, which extends over the entire heating plate 5 extends. Alternatively, other types of suitable heating elements 55 be used. In addition, the heating element 55 preferably consist of smaller heating modules, each extending over only a portion of the heating plate.

As in 1b is shown on the heating plate 5 a buffer layer 3 arranged. The buffer layer 3 For example, it may be made of a cellulosic material such as a sheet of paper or paperboard. A thickness of the buffer layer 3 less than 0.15 mm or less may be sufficient. But depending on the material of the buffer layer 3 For example, thicker layers may be used, for example up to about 0.4 mm or even 1 mm.

After that, as in 1c shown a substrate 1 on the buffer layer 3 arranged. The substrate 1 , which is preferably made of glass or similar rigid material, contacts the buffer layer 3 with the mounting surface 12 , In the arrangement shown here have the substrate 1 and the heating plate 5 about the same size and covers the buffer layer 3 essentially the entire mounting surface 12 of the substrate 1 and therefore essentially the entire heating plate 5 ,

Alternatively, the sizes of the substrate attachment surface 12 and the heating plate 5 differ. In addition, the buffer layer 3 be arranged in such a way that they have only one central area 121 the mounting surface 12 of the substrate 1 covered, creating a border area 122 the mounting surface 12 is left out or only part of it is covered. Covering the middle area 122 the mounting surface 12 is necessary because of the substrate 1 applied stress higher here than near the boundary of the substrate 1 is. Preferably, this comprises the buffer layer 3 covered middle area 121 a central area that is a geometric center of the mounting surface 12 surrounds.

At the in 1c The arrangement shown by the heating element 55 in the hot plate 5 provided heat through the buffer layer 3 to the substrate 1 transferred to the temperature of the substrate 1 to a desired value for the thin film deposition, for example to about 40 ° C, 50 ° C, 60 ° C or a higher temperature, and to hold at this value. In a subsequent deposition step, as in 1d shown a thin film 2 on the substrate 1 deposited. The thin film 2 can be generated using a chemical bath deposition technique.

2 illustrates an embodiment of the manufacturing method and apparatus wherein the substrate 1 by a vacuum, which by a vacuum pump shown here only schematically 7 is provided on the hot plate 5 is held. The vacuum pump 7 may be any suitable pump that can provide sufficient suction to create a vacuum pressure to hold the substrate to the hot plate, preferably a vacuum pressure between about 10 mbar and about 800 mbar.

The suction effect is through suction holes 53 in the hot plate 5 generated. The buffer layer 3 includes holes 33 that with the suction holes 53 aligned to the vacuum pressure to the mounting surface 12 of the substrate 1 transferred to. Alternatively, the buffer layer 3 made of an air-permeable material such as a fibrous material or a fabric, in which case on the holes 33 can be waived. As in connection with 1 described may be the coverage of the mounting surface 12 with the buffer layer 3 from what is in 2 shown is different. In addition, the buffer layer 3 consist of separate buffer layer pieces, which are between the substrate 1 and the heating plate 5 are arranged.

LIST OF REFERENCE NUMBERS

1

substratum

12

Substrate mounting surface

121

the central region the mounting surface

122

border area the mounting surface

2

seasoned Movie

3

buffer layer

33

holes

5

heating plate

53

suction holes

55

heating element

7

vacuum pump

Claims (14)

A thin-film solar cell manufacturing method comprising a step of mounting a substrate ( 1 ) on a hot plate ( 5 ), and a step of depositing a film ( 2 ) on the substrate ( 1 ), wherein during the attaching step a buffer layer ( 3 ) between the heating plate ( 5 ) and a mounting surface ( 12 ) of the substrate ( 1 ) is arranged, the at least one central area ( 121 ) of the substrate attachment surface ( 12 ) covered. Manufacturing method according to claim 1, characterized in that the buffer layer ( 3 ) between the heating plate ( 5 ) and the substrate ( 1 ), wherein substantially the entire substrate mounting surface (FIG. 12 ) is covered. Manufacturing method according to claim 1 and 2, characterized in that between the heating plate ( 5 ) and the substrate ( 1 ) arranged buffer layer ( 3 ) consists of a flexible material. Manufacturing method according to one of the preceding claims, characterized in that between the heating plate ( 5 ) and the substrate ( 1 ) arranged buffer layer ( 3 ) consists of a plastic material. Manufacturing method according to one of claims 1 to 3, characterized in that between the heating plate ( 5 ) and the substrate ( 1 ) arranged buffer layer ( 3 ) consists of a fiber material and / or composite materials. Manufacturing method according to one of the preceding claims, characterized in that between the heating plate ( 5 ) and the substrate ( 1 ) arranged buffer layer ( 3 ) has a thickness of less than about 1 mm, advantageously less than about 0.4 mm, and more preferably less than about 0.15 mm. Manufacturing method according to one of the preceding claims, characterized in that the mounting step comprises providing suction through suction holes ( 53 ) in the hot plate to the substrate ( 1 ) by a vacuum on the heating plate ( 5 ). A manufacturing method according to claim 7, characterized in that said attaching step comprises a step of aligning holes ( 33 ) in the buffer layer ( 3 ), with the suction holes ( 53 ) in the heating plate ( 5 ). Manufacturing method according to claim 7 or 8, characterized in that the vacuum pressure for holding the substrate ( 1 ) on the heating plate ( 5 ) is set to between about 10 mbar and about 800 mbar. Manufacturing method according to one of the preceding claims, characterized in that the substrate ( 1 ) during the deposition of the film ( 2 ) on the substrate ( 1 ) is heated to a temperature above about 40 ° C, preferably above about 50 ° C, and more preferably above about 60 ° C. Manufacturing method according to one of the preceding claims, characterized in that the deposition of the film ( 2 ) on the substrate ( 1 ) is performed by chemical bath deposition (CBD). Manufacturing method according to one of the preceding claims, characterized in that the buffer layer ( 3 ) is arranged by hand or automatically on the heating plate. Manufacturing method according to one of the preceding claims, characterized in that the buffer layer ( 3 ) comprises a self-adhesive surface which during the attachment of the substrate ( 1 ) on the heating plate ( 5 ) is arranged. Manufacturing apparatus for producing thin-film solar cells, comprising a heating plate ( 5 ) used for mounting a substrate ( 1 ) and heating elements ( 7 ), which are constructed to a substrate ( 1 ), a deposition unit designed to form a film ( 2 ) on the substrate ( 1 ) and a buffer layer ( 3 ), so on the hot plate ( 5 ) is arranged during the step of depositing the film ( 2 ) on the substrate ( 1 ) between a mounting surface ( 12 ) of the substrate ( 1 ) and the heating plate ( 5 ), whereby at least one central region ( 121 ) of the substrate attachment surface ( 12 ) covered.

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