1. Field of the Invention
The present invention relates to a fabrication equipment of absorber layer, and more particularly to a vapor deposition equipment for fabricating CIGS films.
2. Description of the Prior Art
Solar cell can be divided into silicon solar cell, compound solar cell, and organic solar cell, wherein the III-V semiconductor compound is widely applied in solar cell, and the solar cell made of single junction GaAs compound performs a better photoelectric conversion efficiency of 26.1±0.8%. However, the solar cell made of multi junction semiconductor compound, for example, GaInP/GaAs/Ge compound, which performs the highest photoelectric conversion efficiency of 32±1.5% than the photoelectric conversion efficiency of the single junction GaAs compound.
Cu/In/Ga/Se (CIGS) is one kind of thin film solar cell and consists of a plurality of semiconductor materials having a variety direct band gaps, wherein the direct band gaps of the semiconductor materials are ranged from 1.04 eV to 1.68 eV. So that, because having the advantages of high light absorption coefficient, broad light absorption range, low manufacturing cost, high stability, and high photoelectric conversion efficiency, the CIGS thin film solar cell is currently a popular solar cell with high potentiality. Please refer to
Generally, the substrate 10′ can be made of a glass material, a thin metal sheet, or a plastic, therefore the CIGS absorber layer 12′, can be largely formed on the flexible substrate 10′ by way of vapor deposition, coating, or print.
However, although the CIGS solar cell includes the advantages of high light absorption coefficient, broad light absorption range, low manufacturing cost, and high stability, there is no a standard manufacturing equipment and the related process procedure for fabricating the CIGS solar cell. On the other hand, the cost of commercial CIGS solar cell is still high due to its poor yield and low photoelectric conversion efficiency, wherein the primary issue is how to largely fabricate the CIGS absorber layer of the CIGS solar cell by using a mass production equipment.
Accordingly, in view of there is no a standard manufacturing equipment and the related process procedure for largely fabricating the CIGS absorber layer of the CIGS solar cell, the inventor of the present application has made great efforts to make inventive research thereon and eventually provided a vapor deposition equipment for fabricating CIGS film.
The primary objective of the present invention is to provide a vapor deposition equipment for fabricating CIGS film, in which a Se vapor deposition module, a In/Ga/In linear vapor deposition module and a Cu linear vapor deposition module are integrated in an identical vacuum chamber, used for fabricating the CIGS absorber layers on a flexible solar cell substrate by an automatic manufacturing process in accordance with an unwinding module, a heating device, a heat reducing device, a speed-controlling roller module, a cooling module, and a winding module. Moreover, in the present invention, a film thickness measuring module is used for measures the thickness of the CIGS chalcopyrite crystalline film on the flexible solar cell substrate, and the thickness data of the CIGS chalcopyrite crystalline film would be transmitted to the electromechanical control module for being references of the parameter modulation of following fabricating process, and such way is so-called APC (Advanced Process Control) system.
Accordingly, to achieve the primary objective of the present invention, the inventor of the present invention provides a vapor deposition equipment for fabricating CIGS film, comprising:
a vacuum chamber, having a vacuum interior formed by using at least one vacuum pump;
an unwinding module, disposed in the vacuum chamber and having an unwinding roller for unwinding a flexible solar cell substrate;
a heating device, disposed in the vacuum chamber and adjacent to the unwinding module, wherein the unwinding module feeds the flexible solar cell substrate to the heating device for being treated the heating process;
a first vapor deposition chamber, disposed in the vacuum chamber, and a first In/Ga/In linear vapor deposition module and a first copper linear vapor deposition module in the first vapor deposition chamber being separated by a first partition plate; wherein an excessive selenium (Se) vapor is flowed into the first In/Ga/In linear vapor deposition module and the first copper linear vapor deposition module, so as to make a
CIGS chalcopyrite crystalline film be formed on the flexible solar cell substrate through the first In/Ga/In linear vapor deposition module and the first copper linear vapor deposition module;
a second vapor deposition chamber, disposed in the vacuum chamber, and a second In/Ga/In linear vapor deposition module and a second copper linear vapor deposition module in the second vapor deposition chamber being separated by a second partition plate; wherein the excessive selenium (Se) vapor is flowed into the second In/Ga/In linear vapor deposition module and the second copper linear vapor deposition module, so as to make an optimized CIGS chalcopyrite crystalline film be formed on the flexible solar cell substrate through the second In/Ga/In linear vapor deposition module and the second copper linear vapor deposition module;
a heat reducing device, being disposed in the vacuum chamber and adjacent to the second vapor deposition chamber, used for preventing the optimized CIGS chalcopyrite crystalline film on the flexible solar cell substrate from cracking due to the residual thermal stress resulted from the rapid temperature change;
a speed-controlling roller module, disposed in the vacuum chamber and located over the unwinding module, wherein a main roller of the speed-controlling roller module is used for winding up the flexible solar cell substrate formed with the optimized CIGS chalcopyrite crystalline film thereon, so as to control the conveying speed of the flexible solar cell substrate in the vacuum chamber;
a cooling module, disposed in the vacuum chamber and located over the heating device, wherein the flexible solar cell substrate formed with the optimized CIGS chalcopyrite crystalline film is transmitted to the cooling module by the speed-controlling roller module for cooling; and
a winding module, disposed in the vacuum chamber and adjacent to the unwinding module via an isolation plate, wherein a winding roller of the unwinding module winds up the flexible solar cell substrate formed with the optimized CIGS chalcopyrite crystalline film for receiving; moreover, the isolation plate is used for preventing the selenium (Se) vapor from flowing into the winding module through the unwinding module directly, so as to protect each of components of the winding module 11a and the flexible solar cell substrate 2 formed with the optimized CIGS chalcopyrite crystalline film from being polluted and damaged by the Se vapor.
The invention as well as a preferred mode of use and advantages thereof will be best understood by referring to the following detailed description of an illustrative embodiment in conjunction with the accompanying drawings, wherein::
To more clearly describe a vapor deposition equipment for fabricating CIGS film according to the present invention, embodiments of the present invention will be described in detail with reference to the attached drawings hereinafter.
Please refer to
The unwinding module 11 is disposed in the vacuum chamber 10 and has a unwinding roller 111 for unwinding a flexible solar cell substrate 2. In addition, the unwinding module 11 further includes an unwinding tension pulley 112 and an edge detecting device 113, wherein the unwinding tension pulley 112 is used for detecting the tension of the flexible solar cell substrate 2 and then adjusting the tension of the flexible solar cell substrate 2 when the flexible solar cell substrate 2 is fed out by the unwinding roller 111, and the edge detecting device 113 is disposed in the vacuum chamber 10 and used for detecting the edge position of the flexible solar cell substrate 2, so as to output an edge position detection signal to a server linear motion system, and then the server linear motion system would execute a linear motion for adjusting the edge position of the flexible solar cell substrate 2 when the flexible solar cell substrate 2 is fed out by the unwinding roller 111.
The winding module 11a is disposed in the vacuum chamber 10 and located over the unwinding module 11 via an isolation plate, wherein the isolation plate is used for preventing the Se vapor from flowing into the winding module 11a through the unwinding module 11 directly, so as to protect each of components of the winding module 11a and the flexible solar cell substrate 2 formed with the optimized CIGS chalcopyrite crystalline film from being polluted and damaged by the Se vapor. In the present invention, a winding roller 111a of the winding module 11a is used to wind up the flexible solar cell substrate 2 formed with an optimized CIGS chalcopyrite crystalline film for receiving. Besides, the winding module 11a further includes a winding tension pulley 112a and an edge detecting device 113a, wherein the winding tension pulley 112a is used for detecting the tension of the flexible solar cell substrate 2 and then adjusting the tension of the flexible solar cell substrate 2 when the flexible solar cell substrate 2 is winded up by the winding roller 111a, and the edge detecting device 113a is used for detecting the edge position of the flexible solar cell substrate 2, so as to output an edge position detection signal to a server linear motion system, and then the server linear motion system would execute a linear motion for adjusting the edge position of the flexible solar cell substrate 2 when the flexible solar cell substrate 2 is winded up by the winding roller 111a.
Herein, it needs to further explain that, both the unwinding module 11 and the winding module 11a at least have a serve motor, which is used for precisely control the tension of the flexible solar cell substrate 2 via the unwinding tension pulley 112 and the winding tension pulley 112a. Moreover, in the present invention, a main roller 161 of the speed-controlling roller module 16 is used for winding up with the flexible solar cell substrate 2 formed with the optimized CIGS chalcopyrite crystalline film thereon, so as to control the conveying speed of the flexible solar cell substrate 2 in the vacuum chamber 10, and control the feeding-out speed of the unwinding module 11 and winding speed of the winding module 11 a at the same time. Therefore, the unwinding module 11 is able to feed the flexible solar cell substrate 2 to the heating device 12 for treating a heating process by a linear feeding-out speed.
Continuously, as shown in
Herein, it needs to further explain that, besides the Se vapor, the vapor flowed into the first In/Ga/In linear vapor deposition module and the first copper linear vapor deposition module can also be Te vapor in order to fabricate a different absorber layer on the flexible solar cell substrate 2. Moreover, the metal compound deposited by the first In/Ga/In linear vapor deposition module can also be an In metal material or a In/Ga metal compound. In addition, besides the Cu metal material, the metal material deposited by the first copper linear vapor deposition module can also be an Al metal material. Furthermore, in this vapor deposition equipment 1, the first In/Ga/In linear vapor deposition module has a plurality of nozzles consisting of two indium vapor nozzles and one gallium vapor nozzle. In the present invention, the two indium vapor nozzles and the gallium vapor nozzle are arranged to focus at the same position on the flexible solar cell substrate 2 in the first vapor deposition chamber 13, so as to form a metal compound of In/Ga/In on the flexible solar cell substrate 2 by a best compound composition ratio.
Opposite to the first vapor deposition chamber 13, the second vapor deposition chamber 14 is disposed in the vacuum chamber 10 and also connected to a diffusion pump, and a second In/Ga/In linear vapor deposition module and a second copper linear vapor deposition module in the second vapor deposition chamber 14 are separated by a second partition plate. When the vapor deposition equipment 1 of the present invention is operated for fabricating a CIGS film, the flexible solar cell substrate 2 formed with the CIGS chalcopyrite crystalline film is subsequently conveyed into the second vapor deposition chamber 14 and treated with a second heating process, and then an excessive selenium (Se) vapor is flowed into the second In/Ga/In linear vapor deposition module and the second copper linear vapor deposition module, so as to make an optimized CIGS chalcopyrite crystalline film composited by a In/Ga/In/Se metal compound and a Cu/Se metal compound be formed on the flexible solar cell substrate 2 through the second In/Ga/In linear vapor deposition module and the second copper linear vapor deposition module.
Similarly, for the second vapor deposition chamber 14, it is not only the Se vapor but also the Te vapor can be flowed into the second In/Ga/In linear vapor deposition module and the second copper linear vapor deposition module for fabricating a different absorber layer on the flexible solar cell substrate 2. Moreover, the metal compound deposited by the second In/Ga/In linear vapor deposition module can also be a In metal material or a In/Ga metal metal compound. In addition, besides the Cu metal material, the metal material deposited by the second copper linear vapor deposition module can also be an Al metal material. Furthermore, in this vapor deposition equipment 1, the second In/Ga/In linear vapor deposition module has a plurality of nozzles, consisting of two indium vapor nozzles and one gallium vapor nozzle. In the present invention, the two indium vapor nozzles and the gallium vapor nozzle are arranged to focus to the flexible solar cell substrate 2 in the second vapor deposition chamber 14, so as to form a metal compound of In/Ga/In on the flexible solar cell substrate 2 by a best compound composition ratio.
However, before the flexible solar cell substrate 2 is conveyed into the second vapor deposition chamber 14, a film thickness measuring module 19 located between the first vapor deposition chamber 13 and the second vapor deposition chamber 14 would measures the thickness of the CIGS chalcopyrite crystalline film on the flexible solar cell substrate 2 formed by the first In/Ga/In linear vapor deposition module and the first copper linear vapor deposition module. Therefore, the thickness data of the CIGS chalcopyrite crystalline film would be transmitted to the electromechanical control module for being references of the parameter modulation of following fabricating process, and such way is so-called APC (Advanved Process Control) system.
Moreover, in the present invention, a heat reducing device 15 is disposed in the vacuum chamber 10 and adjacent to the second vapor deposition chamber 14, used for preventing the optimized CIGS chalcopyrite crystalline film on the flexible solar cell substrate 2 from cracking due to the residual thermal stress resulted from the rapid temperature change. The heat reducing device 15 is designed and established according to the temperature distribution plot of the flexible solar cell substrate 2 shown in
Because the main roller 161 of the speed-controlling roller module 16 is used for controlling the feeding-out speed of the unwinding module 11 and winding speed of the winding module 11a, the contact angle and the friction between the main roller 161 and the flexible solar cell substrate 2 must be analyzed and discussed. Please refer to following table 1, which records the analysis results under three different contact angles of 60°, 90 ° and 180 °. From table 1, it can find that the critical friction coefficient μ is inversely proportional to the contact angle; and it means that the flexible solar cell substrate 2 is more and more difficult to slide on the main roller 161 with the increasing of the contact angle.
Referring to
By above-listed two formulas, the critical friction coefficient can be derived and obtained: μ=4(F2−F1)/3(F2+F1)=1.333(F2−F1)/(F2+F1). Moreover, from
Please refer to
Furthermore, a chemical compound composition measuring module 19a, for example, an XRF (X-Ray Fluorescence) device, which is disposed in the vacuum chamber 10 and located on the accommodating body of the winding module 11a, used for measuring the compound composition of the optimized CIGS chalcopyrite crystalline film on the flexible solar cell substrate 2.
Therefore, through above descriptions, the vapor deposition equipment for fabricating CIGS film of the present invention has been clearly and completely described; in summary, the present invention includes the advantages of:
(1) In the present invention, the Se vapor deposition module, In/Ga/In linear vapor deposition module and Cu linear vapor deposition module are integrated in an identical vacuum chamber, used for fabricating CIGS absorber layer on a flexible solar cell substrate by an automatic manufacturing process in accordance with an unwinding module, a heating device, a heat reducing device, a speed-controlling roller module, a cooling module, and a winding module. Moreover, in the present invention, a film thickness measuring module is used for measures the thickness of the CIGS chalcopyrite crystalline film on the flexible solar cell substrate, and the thickness data of the CIGS chalcopyrite crystalline film would be transmitted to the electromechanical control module for being references of the parameter modulation of following fabricating process, and such way is so-called APC (Advanced Process Control) system.
(2) Inheriting to above point 1, because the Se vapor deposition module, In/Ga/In linear vapor deposition module and Cu linear vapor deposition module are integrated in an identical vacuum chamber, the machine occupation spaces and the manufacturing time cost are largely saved; moreover, in the present invention, the quantity of the vacuum pump is largely reduced due to the decreasing of the requirements for vacuum environment.
(3) Moreover, in the present invention, the server linear motion system is used for executing the linear motion after receiving the edge position detection signal outputted from the edge detecting device 113 of the unwinding module 11 or the edge detecting device 113a of the winding module 11a, such that the edge position of the flexible solar cell substrate 2 would be adjusted through the linear motion of the server linear motion system when the flexible solar cell substrate 2 is fed out by the unwinding roller 111 or winded up by the winding roller 111a.
The above description is made on embodiments of the present invention. However, the embodiments are not intended to limit scope of the present invention, and all equivalent implementations or alterations within the spirit of the present invention still fall within the scope of the present invention.