Patent Application
20110277839
This application claims the priority benefit of Taiwan application serial no. 99115273, filed May 13, 2010. The entirety of the above-mentioned patent application is hereby incorporated by reference herein and made a part of this specification.
The disclosure relates to an anti-reflection coating (ARC) stacked structure and a solar cell having the ARC stacked structure.
An anti-reflection coating (ARC) layer is one of the most important factors for determining the efficiency of various photoelectric devices such as a solar cell. Nowadays, superior ARC layers are fabricated with nano-technology to obtain nano-textured layers.
The fabrication of traditional nano-textured layers is categorized into wet methods and dry methods, both of which are capable of reducing surface reflectivity. However, these methods have their problems. A typical example of using wet methods includes black cells. Although the fabrication cost can be greatly reduced, the nano-textured layers fabricated cannot adjust the thickness of oxide layers quantatively. Thus, effective mass production of the black cells is difficult due to the co-firing of the subsequent cell fabrication. Currently, the highest efficiency of solar cells by using wet methods is about 14% to 15%. In dry methods, on the other hand, expensive processes such as a photolithography process cannot be omitted. Even though high efficiency cells (with efficiency >20%) can be produced therefrom, the use of dry methods remains opposite to the trend of solar cells for pursuing low costs.
The newest nano-textured structures have features similar to graded composition layers and can function as ARC layers suitably. Nevertheless, the tilted angle must be changed during plating the films, which leads to plated films with limited areas and non-uniformity. As a consequence, the fabrication cost is high and mass production cannot be carried out. These drawbacks are not widely accepted by the industry.
The disclosure relates to an anti-reflection coating (ARC) stacked structure capable of reducing the reflectivity and enhancing the efficiency of a photoelectric device such as a solar cell.
The disclosure relates to an ARC stacked structure capable of controlling the thickness and the nano-structure using a simple normal plating method.
The disclosure relates to an ARC stacked structure having a fabrication process capable of operating in co-operation with a subsequent cell fabrication for mass production.
The disclosure relates to a solar cell with superior efficiency.
The disclosure relates to a method of fabricating an ARC layer without requiring the expensive photolithography process.
The disclosure relates to a solar cell including a photoelectric conversion structure and an anti-reflection coating stacked structure on the photoelectric conversion structure. The anti-reflection coating stacked structure includes a first ARC layer and a second ARC layer. The first ARC layer is located on the photoelectric conversion structure. The second ARC layer is formed in fractals and located on the first ARC layer.
The disclosure relates to an anti-reflection coating stacked structure. The anti-reflection coating stacked structure includes a first anti-reflection coating layer and a second anti-reflection coating layer. The first anti-reflection coating layer is a continuous layer. The second anti-reflection coating layer is formed in fractals and located on the first anti-reflection coating layer.
The ARC stacked structure of the disclosure is capable of reducing the reflectivity and enhancing the efficiency of a photoelectric device such as a solar cell.
The ARC stacked structure of the disclosure is capable of controlling the thickness and the nano-structure using a simple normal plating method.
The ARC stacked structure of the disclosure has a fabrication process compatible with subsequent steps of cell processes for mass production.
The disclosure relates to a solar cell with superior efficiency.
Several exemplary embodiments accompanied with figures are described in detail below to further describe the disclosure in details.
The accompanying drawings are included to provide further understanding, and are incorporated in and constitute a part of this specification. The drawings illustrate exemplary embodiments and, together with the description, serve to explain the principles of the disclosure.
Referring to
The first ARC layer 12 is a continuous layer. In an exemplary embodiment, the first ARC layer 12 is a continuous layer and located on a surface 11. The surface 11 can be a textured surface or a planar surface. The first ARC layer 12, for example, is located on a photoelectric conversion layer with a textured surface. Moreover, the first ARC layer 12 and the textured surface are substantially conformed. The textured surface has a shape of a pyramid or a slanted pyramid, or is an irregular surface with bumps. The material of the first ARC layer 12 comprises silicon dioxide, silicon nitride, aluminum oxide, zinc oxide, tin dioxide, or a combination thereof, for example. The first ARC layer 12 can be formed using a plasma enhanced chemical vapor deposition (PECVD) method, a metal-organic chemical vapor deposition (MOCVD) method, a physical vapor deposition (PVD) method, a sputtering deposition method, or an evaporation deposition method, for instance. The first ARC layer 12 has a thickness ranging from about 1 nm to about 100 nm, for example.
The second ARC layer 14 is located on the first ARC layer 12, and a conformation thereof is different from that of the first ARC layer 12. The second ARC layer 14 is formed in fractals, for example, dentritics, three-dimensional networks or a combination thereof as shown in
The second ARC layer 14 can precisely adjust the thickness and the nano-structure by depositing on the surface 11 (textured surface or planar surface) with a simple normal plating method with a tilted angle of 0, such that the second ARC layer 14 does not need to be plated by any tilting angle. The titled angle is an angle between a surface normal direction of the ARC stacked structure 10 and a normal direction of a target for providing source of the second ARC layer 14.
The ARC stacked structure of the exemplary embodiment in the disclosure has a fabrication process compatible with subsequent steps of cell processes for mass production.
The ARC stacked structure of the disclosure can be applied in various photoelectric devices, for example, solar cells, to enhance the performance of solar cells. A solar cell is used as an example in the following for illustration; however, the disclosure is not limited thereto.
Referring to
The photoelectric conversion structure 20 can be any known structure. In one exemplary embodiment, the solar cell 100 is a thin-film solar cell and the photoelectric conversion structure 20 includes a first type substrate 22, a second type doping layer 24, and a first type doping layer 26. The first type substrate 22 includes a surface 22a and a surface 22b. Herein, the surface 22a has the aforementioned textured surface, and the surface 22b has a planar surface. The second type doping layer 24 is located on the surface 22a. A surface of the second type doping layer 24 is the surface 20a, which is conformal to the surface 22a of the first type substrate 22. That is, the surface of the second type doping layer 24 also has a textured surface. A doping concentration of the second type doping layer 24 is higher than a doping concentration of the first type substrate 22. The first type doping layer 26 is located on the surface 22b of the first type substrate 22. A surface of the first type doping layer 26 is the surface 20b. A doping concentration of the first type doping layer 26 is higher than a doping concentration of the first type substrate 22. In one exemplary embodiment, the first type is a P type and the second type is an N type. In another exemplary embodiment, the first type is an N type and the second type is a P type. A dopant of the P type is boron or aluminum, for example, and a dopant of the N type is phosphorus or arsenic, for example. The substrate 22 is made of a semiconductor, for example, silicon.
In one exemplary embodiment, the first electrode 30 is formed in fingers. The first electrode 30 is made of a conductive material, for instance, a metal, an alloy, or a transparent conductive oxide. The metal is silver, aluminum, copper, tin, titanium, palladium, or gold, for example. The alloy is, for instance, silver-aluminum alloy or titanium-palladium-silver alloy. The transparent conductive material is, for example, ITO, ZnO, or SnO2.
In one exemplary embodiment, the second electrode 40 is formed in plane. The second electrode 40 is made of a conductive material, for instance, a metal, an alloy, or a transparent conductive oxide. The metal is aluminum, copper, tin, titanium, palladium, or gold, for example. The alloy is, for instance, silver-aluminum alloy or titanium-palladium-aluminum alloy. The transparent conductive material is, for example, ITO, ZnO, or SnO2.
The ARC stacked structure 10 formed on the surface 20a (light receiving surface) of the photoelectric conversion structure 20 are described in aforementioned embodiment, but not limited thereto. In another embodiment, the ARC stacked structure 10 can also be formed on the surface 20b of the photoelectric conversion structure 20 (shown on
Referring to
The first electrode 30 and the second electrode 40 are also located on the surface 20a and the surface 20b respectively. The materials of the first electrode 30 and the second electrode 40 are as those described above and thus omitted hereinafter. Both first electrode 30 and second electrode 40 have shapes that a light can pass through the photoelectric conversion structure 20. In an embodiment, the first electrode 30 and the second electrode 40 are formed in fingers and are symmetrical so that a light can pass through the photoelectric conversion structure 20. Thus, both surface 20a and surface 20b of the photoelectric conversion structure 20 are light receiving surfaces.
The ARC stacked structure 10′ is located on the surface 20b of the photoelectric conversion structure 20. The ARC stacked structure 10′ includes a first ARC layer 12′ and a second ARC layer 14′. The first ARC layer 12′ is located on the surface 20b. The second ARC layer 14′ is located on a portion of the first ARC layer 12′ and formed in fractals. The second electrode 40 is located on other portion of the first ARC layer 12′. The materials of the first ARC layer 12′ and the second ARC layer 14′ are as the first ARC layer 12 and the second ARC layer 14 described above and thus omitted hereinafter.
Referring to
The first electrode 30 and the second electrode 40 are also located on the surface 20a and the surface 20b respectively. The materials of the first electrode 30 and the second electrode 40 are as those described above and thus omitted hereinafter. Both first electrode 30 and second electrode 40 have shapes that a light can pass through the photoelectric conversion structure 20. In an embodiment, the first electrode 30 and the second electrode 40 are formed in fingers and are symmetrical so that a light can pass through the photoelectric conversion structure 20. Thus, both surface 20a and surface 20b are light receiving surfaces.
The ARC stacked structures 10 and 10′ are located on the surfaces 20a and 20b of the photoelectric conversion structure 20 respectively. The ARC stacked structure 10 includes the first ARC layer 12 and the second ARC layer 14. The first ARC layer 12 is located on the surface 20a. The second ARC layer 14 is located on a portion of the first ARC layer 12 and formed in fractals. The first electrode 30 is located on other portion of the first ARC layer 12. The ARC stacked structure 10′ includes the first ARC layer 12′ and the second ARC layer 14′. The first ARC layer 12′ is located on the surface 20b. The second ARC layer 14′ is located on a portion of the first ARC layer 12′ and formed in fractals. The second electrode 40 is located on other portion of the first ARC layer 12. The materials of the first ARC layers 12 and 12′, and the second ARC layers 14 and 14′ are as those described above and thus omitted hereinafter.
A surface texturization process is performed to a front surface of a P type monocrystalline silicon substrate using potassium hydroxide to generate a pyramid structure. Thereafter, POCl3 is flowed into a high temperature furnace tube for a phosphorus diffusion to form a PN junction. A silicon nitride layer (SiNx) is then plated on the front surface of the P type monocrystalline silicon substrate as a first ARC layer with the plasma enhanced CVD method. Afterwards, ITO nano-dentritics are formed on the SiNx layer on the front surface of the substrate as a second ARC layer. A scanning electron microscope (SEM) is used to observe a conformation of the fabricated sample and measure the reflectivity and the quantum efficiency versus wavelength of an incident light for the fabricated sample as shown in
A sample is fabricated in a manner similar to that in Example 1. However, ITO nano-dentritics acting as the second ARC layer are not formed on the SiNx layer.
The same surface texturization process described in Example 1 is performed to a front surface of a P type monocrystalline silicon substrate to generate a pyramid structure. Thereafter, POCl3 is flowed into a high temperature furnace tube for a phosphorus diffusion to form a PN junction. A SiNx layer is then plated on the front surface of the P type monocrystalline silicon substrate as a first ARC layer. Afterwards, a silver paste and an aluminum paste adopted as electrodes are respectively formed on the front surface and a back surface of the P type monocrystalline silicon substrate by screen printing. Later, ITO nano-dentritics are formed on the SiNx layer on the front surface of the substrate as a second ARC layer. A co-firing process is then preceded. An electrical characteristic measurement (current density versus voltage) is performed, and the results thereof are illustrated in Table 1 and
A sample is fabricated in a manner similar to that described in Example 2, but ITO nano-dentritics are not formed on the SiNx layer on the front surface of the substrate. An electrical characteristic measurement (current density versus voltage) is performed, and the results thereof are illustrated in Table 1 and
A sample is fabricated in a manner similar to that described in Example 2, but ITO nano-rods are instead of ITO nano-dentritics. An electrical characteristic measurement is performed, and the results thereof are illustrated in Table 2. The SEM image of this sample is shown in
As shown from the SEM results, the ITO in Example 1 is formed in nano-dentritics, and short branches with a length of about 655 nm can be observed on the surface of the nano-pillar structure.
The results in
From the results in
From the results in
From the results in
In summary, the ARC stacked structure with nano-fractals of the disclosure is capable of reducing the reflectivity and enhancing the efficiency of an photoelectric device such as a solar cell. In addition, the ARC stacked structure with nano-fractals of the disclosure can precisely adjust the thickness and the nano-fractals by utilizing a simple normal plating method, such that the film does not need to be plated by any tilting angle. Moreover, the costly photolithography process can be omitted so as to reduce fabrication cost. Furthermore, the ARC stacked structure with nano-fractals of the disclosure has a fabrication process capable of operating in co-operation with a subsequent solar cell fabrication for mass production. Consequently, the solar cell has superior efficiency and the fabrication cost can be greatly reduced. The solar cell can thus be more competitive in the market. Also, the ARC stacked structure with nano-fractals of the disclosure has the potential to be applied in solar cells of thin-film, MWT, EWT, IBC, or HIT for greatly enhancing the efficiency.
It will be apparent to those skilled in the art that various modifications and variations can be made to the structure of the disclosed embodiments without departing from the scope or spirit of the disclosure. In view of the foregoing, it is intended that the disclosure cover modifications and variations of this disclosure provided they fall within the scope of the following claims and their equivalents.
| Number | Date | Country | Kind |
|---|---|---|---|
| 99115273 | May 2010 | TW | national |
