TWI481059B - Annealing device for a thin-film solar cell - Google Patents

Description

Thin film solar cell annealing device

The present invention relates to an annealing apparatus for a thin film solar cell, and more particularly to an annealing apparatus for improving uneven heating of a thin film solar cell.

CIGS (copper indium gallium (di) selenide) in thin film solar cells belongs to compound semiconductors. CIGS is in the form of a polycrystalline film, which is a group of three or five compound semiconductor materials composed of copper, indium, gallium and selenium. Figure 1A shows a schematic diagram of one of the steps in the fabrication of a CIGS thin film solar cell. Figure 1B shows a schematic diagram of one of the steps in the fabrication of a CIGS thin film solar cell. As shown in FIG. 1A, the CIGS thin film solar cell 10 includes a glass substrate 11. A molybdenum metal layer 12, a copper gallium metal layer 13, an indium metal layer 14, and a selenium layer 15 are sequentially deposited on the glass substrate 11. As shown in FIG. 1B, the CIGS thin film solar cell 10 of the step of FIG. 1A is subjected to an annealing treatment, and the annealing mainly refers to a process of exposing the material to a high temperature for a period of time and then slowly cooling, after annealing, The copper gallium metal layer 13, the indium metal layer 14, and the selenium layer 15 form a CIGSe layer 16.

2A shows an external junction of an annealing device of a conventional thin film solar cell Schematic diagram of the structure. The annealing device 20 for a thin film solar cell includes five annealing chambers 21 to 25 and two cooling chambers 31 to 32 that communicate with each other. When the annealing treatment is performed, the CIGS thin film solar cell 10 shown in FIG. 1A is sent from the inlet 35 of the annealing device 20 to the annealing chamber 21 for preheating, and then sent to the annealing chamber 22 by a transfer device (not shown). Heat to a high temperature state, for example, 500 ° C ~ 600 ° C. The CIGS thin film solar cell 10 is maintained in a high temperature state for a while in the annealing chamber 23. The CIGS thin film solar cell 10 is started to be cooled in the annealing chamber 24, and finally, the CIGS thin film solar cell 10 is slowly cooled to a low temperature state in the cooling chambers 31 to 32, and then sent out from the outlet 36.

2B is a schematic view showing the internal structure of each annealing chamber of an annealing device of a conventional thin film solar cell. As shown in FIG. 2B, a bottom plate 26 is provided in the annealing chamber 21. The CIGS thin film solar cell 10 is placed on the bottom plate 26. A heater 50 heats the CIGS thin film solar cell 10 via a cover plate 60.

Figure 3 shows a schematic view of a conventional transfer device for a thin film solar cell annealing apparatus. As shown in FIG. 3, a conventional thin film solar cell annealing apparatus 40 is disposed in the bottom plate 26 of the annealing chambers 21 to 25 for transporting the CIGS thin film solar cell 10 (i.e., its glass substrate 11). The transfer device 40 of the conventional thin film solar cell annealing device comprises at least one roller 41, at least one push rod 44 and at least one abutment rod 43. The roller 41 is disposed on the bottom plate 26 of each of the annealing chambers 21-25. Preferably, most of the rollers 41 are disposed in the bottom plate 26, and a small portion is exposed. The portion protrudes from the bottom plate 26 to make the CIGS thin film solar cell 10 The back surface of the glass substrate 11 can be moved on the roller 41 without coming into contact with the bottom plate 26.

In the conventional example of Fig. 3, two cylindrical push rods 44 are used, which are respectively located in the right and left halves of the bottom plate 26 and do not protrude from the bottom plate 26. The abutment rod 43 is provided to the push rod 44, and the push rod 44 is placed in the push rod guide groove 45. In the stationary state (not shown) of the conveyor 40, the abutment rod 43 is located in the recess 27 and is in a state of not protruding from the bottom plate 26. In the transport state of the transport device 40, as shown in FIG. 3, the push lever 44 is rotated counterclockwise by a predetermined angle, for example, 90 degrees, so that the abutment lever 43 protrudes from the bottom plate 26. As the push rod 44 moves toward the next annealing chamber, the glass substrate 11 of the CIGS thin film solar cell 10 will abut against the abutment rod 43 and move with the push rod 44 on the roller 41. When both the push rod 44 and the glass substrate 11 are moved to the next annealing chamber, the push rod 44 is rotated clockwise (not shown), so that the abutting rod 43 is in the other recess 27, and returns to the bottom plate without protruding. In the state of 26, after the push rod 44 is retracted to the current annealing chamber, the transfer operation of the CIGS thin film solar cell 10 between the annealing chambers 21 to 25 is completed.

However, the CIGS thin film solar cell 10a formed by the conventional annealing device 20 reduces the quality and yield of the CIGS thin film solar cell 10a due to uneven heating. Therefore, the conventional annealing device 20 has room for further improvement.

An object of an embodiment of the present invention is to provide an annealing apparatus for a thin film solar cell.

According to an embodiment of the invention, a thin film solar cell annealing device is provided for performing an annealing process on a thin film solar cell comprising a Group VIA element. The thin film solar cell annealing apparatus includes at least one annealing chamber. Each annealing chamber includes a bottom plate, a heater, and a transfer device. The bottom plate is used to place a thin film solar cell containing a Group VIA element. The heater is used to heat a thin film solar cell containing a Group VIA element. The transfer device is configured to transport a thin film solar cell containing a Group VIA element, and the heat transfer amount of the transfer device is higher than the heat transfer amount of the bottom plate.

In one embodiment, the conveying device comprises a plurality of rollers, the roller is disposed in the bottom plate, and a first portion is exposed from the bottom plate, the first portion protrudes from the bottom plate, and the rollers of the conveying device have a higher thermal conductivity than the porous three-phase oxidation The thermal conductivity of aluminum.

In one embodiment, the heat transfer coefficient of the conveyor is substantially greater than or equal to about 16.0 W/m ⁰ k. In one embodiment, the material of the transfer device is tantalum carbide (SiC).

In one embodiment, the heat transfer coefficients of the rollers in the annealing chamber of the warming section are greater than the heat transfer coefficients of the rollers in the annealing chamber of the cooling section.

In one embodiment, the rollers in an annealing chamber and the included The relative position between the thin film solar cells of the VI group A element is different from the relative position between the rollers in the other annealing chamber and the thin film solar cell containing the Group VI A element.

In an embodiment, the conveying device further comprises at least one push rod and at least one abutting rod. The push rod is disposed on the bottom plate for moving along a transport path of the thin film solar cell including the Group VIA element. The abutment rod is disposed on the push rod, wherein the push rod is used to rotate against the rod such that the abutment rod is selectively located within the transport path of the thin film solar cell containing the Group VIA element or outside the transport path.

In an embodiment, the bottom plate defines at least one push rod guide groove, and the at least one push rod is located in the at least one push rod guide groove.

According to an embodiment of the present invention, since the heat transfer amount of the transfer device is higher than or equal to the heat transfer amount of the bottom plate, it is preferable that the heat transfer coefficient of the rollers of the transfer device is higher than the heat transfer coefficient of the porous alumina. Therefore, it is possible to improve the occurrence of voids in the semiconductor board generated by the conventional technique.

In one embodiment, the rollers have a heat transfer coefficient substantially greater than or equal to about 16.0 W/m ⁰ k. Preferably, the rollers are made of uniformly dense aluminum oxide, and the dense aluminum oxide has a density greater than or equal to 3.4 G/cm 3 and a purity greater than or equal to 85%. In one embodiment, the rollers of the conveyor are made of tantalum carbide (SiC).

In an embodiment, the bottom plate includes a plurality of roller cover plates and defines a plurality of rollers a slot for receiving the rollers, the roller cover covers the roller slots and exposing the rollers, and the height of the roller covers is higher than the height of the surface of the bottom plate, but lower The height of the apex of the rollers is used to increase the heat transfer without affecting the transmission of the thin film solar cell.

In an embodiment, the heat transfer coefficient of the rollers in the annealing chamber of the heating section is greater than the heat transfer coefficient of the rollers in the annealing chamber of the cooling section, thereby reducing the difference in process conditions between the heating section and the cooling section. The uneven heating caused. In one embodiment, the relative positions of the rollers in an annealing chamber and the thin film solar cell including the Group VIA element are different from the rollers in the other annealing chamber and the group VIA The relative position between the thin film solar cells of the elements can therefore reduce the accumulation of internal stress.

Other objects and advantages of the present invention will become apparent from the technical features disclosed herein. The above and other objects, features, and advantages of the invention will be apparent from

4 is a schematic view showing an annealing apparatus of a thin film solar cell according to an embodiment of the present invention. As shown in FIG. 4, the thin film solar cell annealing apparatus 100 is configured to perform an annealing process on a CIGS thin film solar cell 10, which includes at least one retreat. Fire room 110. Each annealing chamber 110 includes a bottom plate 130, a heater 150, a cover plate 160, and a transfer device 120.

The bottom plate 130 is used to place the CIGS thin film solar cell 10 and the transfer device 120. The heater 150 is used to heat the CIGS thin film solar cell 10 via the cover plate 160, and the transfer device 120 is used to transport the CIGS thin film solar cell 10. In one embodiment, the heater 150 can be placed within the bottom plate 130 and the cover plate 160. Further, the heat transfer amount of the conveying device 120 is higher than or equal to the heat transfer amount of the bottom plate 130. More specifically, it is generally the case that the material of the bottom plate 130 is graphite. In one embodiment, the transport device 120 can include a roller 121 and a push rod (not shown). And the heat transfer coefficient of the rollers 121 of the conveying device 120 is higher than the heat transfer coefficient of the porous alumina.

Figure 5 shows a schematic of a CIGS thin film solar cell after annealing using a conventional annealing device. As shown in FIG. 5, the conventionally annealed device 40 is used to complete the annealed CIGS thin film solar cell 10a, and the spots thereon can be roughly divided into a dot spot 51 and a strip spot 52. Referring again to FIG. 3, in general, the bottom plate 26 of the annealing chamber is made of graphite, and the material of the roller 41 is not graphite. The material of the roller 41 is a conventional alumina, that is, porous alumina, which is pushed. In the region of the rod 44, the bottom plate 26 also needs to form the push rod guide groove 45, and there is a gap between the push rod 44 and the push rod guide groove 45. These factors cause the CIGS thin film solar cell 10a to be unevenly heated, so the CIGS film A portion of the corresponding roller 41 of the solar cell 10a forms a spotted spot 51, and a portion corresponding to the pusher bar 44 forms a strip-like spot 52. The conventional alumina is made of porous alumina with a density of 2.0 to 2.5 G/cm ³ and a heat transfer coefficient of 3.1 W/m ⁰ k.

In contrast, in one embodiment of the present invention, the heat transfer amount of the transfer device 120 is higher than or equal to the heat transfer amount of the bottom plate 130. Preferably, the material of the roller 121 of the transfer device 120 adopts a heat transfer coefficient higher than that. The material of the thermal conductivity of the pore aluminum oxide can improve the photoelectric conversion efficiency of the CIGS thin film solar cell 10a. More specifically, for example, stainless steel may be used which has a heat transfer coefficient of 6 W/m ⁰ k.

However, according to experiments by the inventors, it is preferred to use dense aluminum oxide, which means that the density is greater than or equal to 3.4 G/cm ³ and the purity is greater than or equal to 85%. Aluminum oxide. For the types of dense aluminum oxide, reference can be made to Table 1 below.

In addition, in one embodiment, for example, lanthanum carbide (SiC) can be used, and the heat transfer coefficient of the tantalum carbide is 150 W/m ⁰ k, and the heat transfer coefficients of the materials are higher than the heat transfer coefficient of the conventional alumina of 3.1 W/m. ⁰ k, therefore, the photoelectric conversion efficiency of the CIGS thin film solar cell 10a can be improved. According to experiments by the inventors, it is found that a better photoelectric conversion efficiency can be obtained with a heat transfer coefficient of 20 W/m ⁰ k or more. Therefore, it is preferred to use a dense aluminum oxide having a density of greater than or equal to 3.7 G/cm ³ and a purity of greater than or equal to 96%.

Figure 6A shows a scanning electron microscope (SEM) image of a spot of a CIGS thin film solar cell after annealing according to a conventional annealing apparatus. 6B is an electron micrograph showing spots of a CIGS thin film solar cell after annealing in accordance with an annealing apparatus according to an embodiment of the present invention. As shown in FIG. 6A, the CIGS thin film solar cell 10a produced by the conventional annealing device 40 has a large number of voids formed in the CIGSe layer 16. According to research by the inventors, the voids affect the photoelectric conversion efficiency of the CIGS thin film solar cell 10a.

In order to improve the formation of voids in the CIGSe layer 16, the inventors attempted to change the material of the roller 121 of the transport device 120 and use various possible materials, as shown in FIG. 6B, when using tantalum carbide as the material of the roller 121 of the transport device 120. There has been a significant improvement in voids in the CIGSe layer 16. The reason is that the thermal conductivity of the porous aluminum oxide and the thermal conductivity of the graphite are largely different, which causes the CIGS thin film solar cell 10 to be unevenly heated. In particular, the porous aluminum oxide has a heat transfer coefficient of about 3.1 W/m ⁰ k, and the thermal conductivity is low, so the temperature of the roller 121 of the conveying device 120 is low, since the roller 121 of the conveying device 120 directly contacts the CIGS thin film solar energy. The battery 10 thus forms a void in the CIGSe layer 16 of the contact portion.

It is known from the implementation results that the roller 121 of the conveying device 120 should use a material having a higher thermal conductivity than the porous aluminum oxide to improve the uneven heating. Preferably, the roller 121 of the transfer device 120 is made of a material having a heat transfer coefficient substantially greater than or equal to about 16 W/m ⁰ k, such as tantalum carbide (SiC), a graphite, or a dense aluminum oxide having a density greater than or equal to 3.4 G/cm ³ has a purity greater than or equal to 85%. It is preferred to use a dense aluminum oxide having a density of greater than or equal to 3.7 G/cm ³ and a purity of greater than or equal to 96%.

It should be understood that the present invention is not limited to the type of roller 121 of the conveyor 120. In one embodiment, the roller 121 and the push rod may be used. In other embodiments, currently available or future developed conveyors may be used.

In addition, the annealing process is a process from temperature rising to cooling, so the annealing chambers 110 can be divided into a heating section and a cooling section. Therefore, it is preferable that the material of the roller 121 of the conveying device 120 of the heating section is higher than the material of the roller 121 of the conveying device 120 of the temperature decreasing section. And preferably, the heat transfer coefficient of the rollers 121 in the annealing chamber 110 of the warming section is greater than the heat transfer coefficient of the rollers 121 in the annealing chamber 110 of the temperature decreasing section.

More specifically, in order to heat the CIGS thin film solar cell 10 on average, it is necessary to have uniform heat exchange between each portion of the CIGS thin film solar cell 10 and the external environment.

In one embodiment, it is preferred that the heat transfer rates for the temperature rise and the temperature decrease are substantially equal. More specifically, in the annealing chamber 110 of the temperature rising section, the rate of temperature rise is faster, and the roller 121 needs to be heated as much as possible to be substantially equal to the temperature in the chamber of the annealing chamber 110, and therefore it is necessary to have a better heat transfer coefficient. In this way, the difference between the heat transfer amounts of the temperature rise and the temperature drop can be reduced, and the CIGS thin film solar cell 10 after passing through the temperature rising section and the temperature decreasing section can be uniformly heated to reduce the internal stress generated by the heat.

According to the prior art, the relative positions of the rollers 41 and the CIGS thin film solar cells 10 in the annealing chambers 21 to 25 are substantially the same, that is, the rollers 41 in the annealing chambers 21 to 25 are substantially in contact with the same of the CIGS thin film solar cells 10. section. However, after a plurality of annealing chambers 21 to 25, the uneven heating phenomenon accumulated for a long period of time causes the internal contact between the contact portion and the other portions of the CIGS thin film solar cell 10 to have a large heat. It is easy to cause the glass to bend or even rupture. Therefore, as shown in FIG. 4, according to an embodiment of the invention, the relative positions between the rollers 121 and the CIGS thin film solar cells 10 in an annealing chamber 110 can be different from those in the other annealing chamber 110. The relative position between the roller 121 and the CIGS thin film solar cell 10. This can reduce the accumulation of internal stress and can reduce multiple times. Thermal unevenness causes problems and defects caused by accumulation of internal stress.

In one embodiment, the heater 150 is disposed in the annealing chamber 110 to heat the CIGS thin film solar cell 10 via the cover plate 160 and includes a plurality of heating tubes 151. The heating tube 151 is elongated and has a long axis extending in a second direction. Preferably, the second direction is substantially perpendicular to the conveying direction of the CIGS thin film solar cell 10, that is, the first direction D1. In addition, the bottom plate 130 defines at least one push rod guide (see FIG. 3), and the push rod is located within the push rod guide.

Further, although the present invention is described by taking the CIGS thin film solar cell 10 containing selenium as an example, the present invention is not limited thereto, and selenium is a Group VIA element, and therefore, those skilled in the art can understand that the present invention can also be understood. It can be applied to a thin film solar cell containing a Group VIA element.

While the present invention has been described in its preferred embodiments, the present invention is not intended to limit the invention, and the present invention may be modified and modified without departing from the spirit and scope of the invention. The scope of protection is subject to the definition of the scope of the patent application. In addition, any of the objects or advantages or features of the present invention are not required to be achieved by any embodiment or application of the invention. In addition, the abstract sections and headings are only used to assist in the search of patent documents and are not intended to limit the scope of the invention.

10‧‧‧CIGS thin film solar cells

100‧‧‧Thin film solar cell annealing device

10a‧‧‧CIGS thin film solar cell

11‧‧‧ glass substrate

110‧‧ anneal room

12‧‧‧Molybdenum metal layer

120‧‧‧Transfer device

121‧‧‧Roller

13‧‧‧copper gallium metal layer

130‧‧‧floor

14‧‧‧Indium metal layer

15‧‧‧Selenium

150‧‧‧heater

151‧‧‧heat pipe

16‧‧‧CIGSe layer

160‧‧‧ cover

20‧‧‧ Annealing device

21~25‧‧‧ Annealing Room

26‧‧‧floor

27‧‧‧ Groove

31~32‧‧‧ Cooling room

35‧‧‧ entrance

36‧‧‧Export

40‧‧‧Transfer

41‧‧‧Roller

42‧‧‧Roller cover

43‧‧‧Abutment rod

44‧‧‧Pushing rod

45‧‧‧Pushing rod guide

50‧‧‧heater

51‧‧‧ spotted spots

52‧‧‧ strip spots

60‧‧‧ cover

Figure 1A shows one step of the manufacturing process of a CIGS thin film solar cell schematic diagram.

Figure 1B shows a schematic diagram of one of the steps in the fabrication of a CIGS thin film solar cell.

2A is a schematic view showing the external structure of an annealing device of a conventional thin film solar cell.

2B is a schematic view showing the internal structure of each annealing chamber of an annealing device of a conventional thin film solar cell.

Figure 3 shows a schematic view of a conventional transfer device for a thin film solar cell annealing apparatus.

4 is a schematic view showing an annealing apparatus of a thin film solar cell according to an embodiment of the present invention.

Figure 5 shows a schematic of a CIGS thin film solar cell after annealing using a conventional annealing device.

Figure 6A shows an electron micrograph of a spot of a CIGS thin film solar cell after annealing is completed in accordance with a conventional annealing apparatus.

6B is an electron micrograph showing spots of a CIGS thin film solar cell after annealing in accordance with an annealing apparatus according to an embodiment of the present invention.

10‧‧‧CIGS thin film solar cells

100‧‧‧Thin film solar cell annealing device

110‧‧ anneal room

120‧‧‧Transfer device

121‧‧‧Roller

130‧‧‧floor

150‧‧‧heater

160‧‧‧ cover

Claims (10)

A thin film solar cell annealing device for annealing a thin film solar cell comprising a Group VIA element, the thin film solar cell annealing device comprising at least one annealing chamber, and each annealing chamber comprises: a bottom plate for placing a thin film solar cell comprising a Group VIA element; a heater for heating the thin film solar cell containing the Group VIA element; and a transfer device for transporting the thin film solar energy containing the Group VIA element A battery, wherein the heat transfer coefficient of the transfer device is higher than or equal to a heat transfer coefficient of the bottom plate. The thin film solar cell annealing device of claim 1, wherein the conveying device comprises: a plurality of rollers disposed in the bottom plate and exposing a first portion from the bottom plate, the first portion protruding from the bottom plate, and The rollers of the conveyor have a thermal conductivity higher than that of the porous alumina. The thin film solar cell annealing device of claim 2, wherein the rollers have a heat transfer coefficient substantially greater than or equal to about 16.0 W/m ⁰ k. The thin film solar cell annealing device according to claim 3, wherein the rollers are made of uniformly dense aluminum oxide, and the density of the dense aluminum oxide is greater than or equal to 3.4 G/cm ³ . Its purity is greater than or equal to 85%. The thin film solar cell annealing device of claim 2, wherein the bottom plate comprises a plurality of roller cover plates and defines a plurality of roller grooves, wherein the roller grooves are used for accommodating the rollers, and the roller cover covers Holding the roller grooves and exposing the rollers, and the height of the roller cover is higher than the height of the surface of the bottom plate, but lower than the height of the apex of the rollers, thereby increasing the heat transfer amount and not affecting the thin film solar energy Battery transfer. The thin film solar cell annealing device of claim 3, wherein the rollers of the transfer device are made of tantalum carbide (SiC). The thin film solar cell annealing device of claim 2, wherein the rollers in the annealing chamber of the heating section have a heat transfer coefficient greater than a heat transfer coefficient of the rollers in the annealing chamber of the temperature decreasing section. The thin film solar cell annealing device according to claim 7, wherein the relative positions of the rollers in an annealing chamber and the thin film solar cell containing the Group VI A element are different from the other annealing chamber. The relative positions of the rollers in the film and the thin film solar cell containing the Group VI A element. Thin film solar cell annealing package as described in claim 2 The transport device further includes: at least one push rod disposed on the bottom plate for moving along a transport path of the thin film solar cell containing the Group VI A element; and at least one abutting rod disposed at the At least one push rod, wherein the at least one push rod is used to selectively position the at least one abutting rod in the transport path of the thin film solar cell containing the Group VI A element or outside the transport path. The thin film solar cell annealing device of claim 9, wherein the bottom plate defines at least one stacking rod guiding groove, and the at least one pushing rod is located in the at least one pushing rod guiding groove.