TWI492409B - Manufacturing method of solar cell - Google Patents

Description

Solar cell manufacturing method

The present invention relates to a solar cell, and more particularly to a method of fabricating a solar cell.

Common solar cells are usually made of a semiconductor material, such as a twinned material. When the sun's rays enter the solar cell, the semiconductor material absorbs the light energy and internally generates an electron-hole pair, which separates the electron-hole pair through the built-in electric field, so that the solar cell can obtain power.

In general, there are many defects on the surface of the twinned material, such as dangling bonds, which trap the pair of electron holes generated by the solar cell and reduce the photoelectric conversion efficiency of the solar cell. In this regard, some industries have sought to reduce the surface recombination rate by forming a passivation layer to reduce the number of electron hole pairs captured by the surface of the twinned material.

Embodiments of the present invention provide a method of fabricating a solar cell for reducing the fabrication cost of the passivation layer and the anti-reflection layer.

Embodiments of the present invention provide a method of fabricating a solar cell, the method of manufacturing the solar cell comprising providing a substrate, wherein the substrate comprises a first conductive semiconductor layer and a second conductive semiconductor layer, wherein the first conductive semiconductor layer and the second The conductive semiconductor layer has opposite conductivity. A graphene oxide layer is formed on the substrate, and the graphene oxide layer is in contact with the second conductive type semiconductor layer. The first electrode and the second electrode are formed on the substrate, and the first electrode is in contact with the first conductive semiconductor layer, and the second electrode is in contact with the second conductive semiconductor layer.

In summary, in the method for fabricating a solar cell according to an embodiment of the present invention, a graphene oxide layer is formed on a substrate, and the graphene oxide layer is in contact with the second conductive semiconductor layer. The graphene oxide layer can be used not only as a passivation layer of a solar cell, but also to reduce the electron-hole recombination rate of the surface of the solar cell. The graphene oxide layer can also serve as an anti-reflection layer of the solar cell to reduce the incident light of the solar cell. The reflectivity, thereby increasing the incident light that the solar cell can absorb, thereby improving the photoelectric conversion efficiency of the solar cell. In addition, the graphene oxide layer is formed by immersing the substrate in the graphene oxide suspension solution. Therefore, the process of the graphene oxide layer is relatively simple, and the manufacturing cost of forming the passivation layer and the anti-reflection layer of the solar cell can be reduced.

In order to further understand the technology, method and effect of the present invention in order to achieve the intended purpose, reference should be made to the detailed description and drawings of the present invention. The drawings and the annexed drawings are intended to be illustrative and not to limit the invention.

100‧‧‧ solar cells

110‧‧‧Substrate

112‧‧‧First Conductive Semiconductor Layer

114‧‧‧Second conductive semiconductor layer

120‧‧‧ Graphene oxide layer

130‧‧‧First electrode

140‧‧‧second electrode

L1~L4‧‧‧ Curve

S101~S105‧‧‧Step procedure

1 is a schematic structural view of a solar cell according to an embodiment of the present invention.

2 is a flow chart showing a method of manufacturing a solar cell according to an embodiment of the present invention.

3 is a graph showing a reflectance-wavelength curve of a solar cell according to an embodiment of the present invention.

4 is a voltage-capacitance curve diagram of a solar cell according to an embodiment of the present invention.

1 is a schematic structural view of a solar cell according to an embodiment of the present invention, and FIG. 2 is a schematic flow chart of a method for manufacturing a solar cell according to an embodiment of the present invention. Please refer to FIG. 1 and FIG. 2 together.

The solar cell 100 includes a substrate 110, a graphene oxide layer 120, a first electrode 130, and a second electrode 140. The graphene oxide layer 120 is located above the substrate 110, and the first electrode 130 and the second electrode 140 are in contact with the substrate 110, respectively. It should be noted that the manufacturing method of the solar cell 100 mainly forms the graphene oxide layer 120 on the substrate 110 and forms the first electrode 130 and the second electrode 140 on the substrate 110. Accordingly, the solar cell 100 is substantially formed.

First, in step S101, the substrate 110 is provided. The substrate 110 includes a first conductive type semiconductor layer 112 and a second conductive type semiconductor layer 114, wherein the first conductive type semiconductor layer 112 is opposite to the conductivity type of the second conductive type semiconductor layer 114. It is to be noted that the first conductive semiconductor layer 112 is mainly an n-type semiconductor layer doped with a Group 5 element, and the second conductive semiconductor layer 114 is mainly a p-type semiconductor layer doped with a Group III element.

Generally, the substrate 110 is a tantalum substrate which may be a single crystal germanium, a polycrystalline germanium or an amorphous germanium material, and further includes other non-antimony solar light absorbing materials. In the embodiment of the present invention, the substrate 110 is a single crystal germanium, and the first conductive semiconductor layer 112 is in contact with the second conductive semiconductor layer 114, so that a p-n junction can be formed between the two. However, in other embodiments of the invention, the substrate 110 may be an amorphous germanium material, and the substrate 110 may further include an intrinsic semiconductor layer or a low doped semiconductor layer (not shown), wherein the first conductive semiconductor layer 112 and the second The conductive semiconductor layers 114 are respectively located on both sides of the intrinsic semiconductor layer. Accordingly, the solar cell 100 can convert the absorbed light energy into electrical energy by the photovoltaic effect. However, the present invention does not limit the material of the substrate 110.

Further, in order to increase the polarity of the surface of the substrate 110, the substrate 110 may be subjected to surface treatment. In detail, in step S102, the substrate 110 is immersed in the SCl solution, and the SCl solution includes ammonium hydroxide (NH4OH), hydrogen peroxide (H2O2), and deionized water (DI water), and hydroxide. The ratio between ammonium, hydrogen peroxide, and deionized water ranges from 1:1:6 to 1:2:8. It is worth noting that since the SCl solution has an OH functional group and the OH functional group is a polar covalent bond. Accordingly, the surface of the substrate 110 after the SCl solution is immersed has a polarity. Although the substrate 110 is subjected to surface treatment in the embodiment of the present invention, the present invention is not limited thereto.

In step S103, the graphene oxide layer 120 is formed on the substrate 110, and the graphene oxide layer 120 is in contact with the second conductive semiconductor layer 114. In this embodiment, the substrate 110 is immersed in a graphene oxide suspension solution to form a graphene oxide layer. 120. Specifically, the graphite is first oxidized to form graphite oxide, which can be obtained by adding graphite to sulfuric acid (H 2 SO 4 ) and potassium permanganate (KMnO 4 ) to obtain graphite oxide, and oxidizing it by hydrogen peroxide. Next, the graphite oxide is placed in deionized water to form a graphite oxide solution. Next, the first ultrasonic wave oscillation process and the first centrifugation process are performed on the graphite oxide solution by an ultrasonic oscillator and a centrifugation, wherein the first ultrasonic wave oscillation processing time is between 20 and 60 minutes, and the first centrifugation process The rotational speed is between 500 and 15,000 revolutions per minute (rpm), and the first centrifugation time is between 20 and 60 minutes. Accordingly, the graphite oxide solution forms a graphene oxide suspension solution.

It is worth noting that the size of the graphene oxide fragments depends on the time or the number of times of the ultrasonic oscillation treatment and the centrifugation treatment, and the size of the graphene oxide fragments can be changed by adjusting the time or the number of times of the ultrasonic oscillation treatment and the centrifugation treatment. Thus, in order to reduce the size of the graphene oxide fragments, the second ultrasonic wave oscillation treatment may be performed on the graphite oxide suspension solution, and the second ultrasonic vibration treatment time is between 60 and 150 minutes, and then the second centrifugal treatment is performed every minute. At 500 to 15000 (revolutions per minute, rpm), the second centrifugation time is between 20 and 60 minutes. However, the present invention does not limit the conditions of the ultrasonic oscillation processing and the centrifugal processing.

Next, the partial graphene oxide suspension solution is taken out through the dropper, the graphene oxide suspension solution is dropped on the surface of the substrate 110, or the substrate 110 is immersed in the graphene oxide suspension solution, so that the second conductive type semiconductor layer 114 It is accessible to the graphene oxide suspension solution. Then, the substrate 110 provided with the graphene oxide suspension solution is air-dried, and the air drying method may be natural air drying or heat drying, which is not limited in the present invention. According to this, the graphene oxide fragments are deposited on the tantalum substrate 110, and the graphene oxide layer 120 is in contact with the second conductive type semiconductor layer 114 to form the graphene oxide layer 120.

However, in other embodiments, the graphene oxide layer 120 may be formed by chemical vapor deposition, mechanical exfoliation, or epitaxial growth, or may be formed first. The graphene is further formed by functional bonding such as oxidation.

Further, it is worth noting that the graphene oxide has a polar bond, and thus, when the graphene oxide fragments are deposited on the surface of the surface-treated second conductive type semiconductor layer 114, the graphene oxide fragments are more uniformly distributed.

In step S105, the first electrode 130 is formed with the second electrode 140 on the substrate 110. As shown in FIG. 2 , the first electrode 130 is disposed on the first conductive semiconductor layer 112 and is in contact with the first conductive semiconductor layer 112 . The second electrode 140 passes through a partial region of the graphene oxide layer 120 and is in contact with the second conductive type semiconductor layer 114.

In detail, the first electrode 130 and the second electrode 140 may be a conductive material, such as silver, aluminum, or the like, formed on the substrate 110 by deposition or coating. For example, the second electrode 140 may be a silver paste coated on the graphene oxide layer 120, and through the heat treatment, the second electrode 140 may pass through the gap between the graphene oxide fragments and the second conductive type semiconductor layer. 114 contact. In addition, the graphene oxide layer 120 may also be a pattern layer having a plurality of holes, which may expose a portion of the second conductive type semiconductor layer 114, and the second electrode 140 is formed on the graphene oxide layer 120 and is transparent to the hole and The second conductive type semiconductor layer 114 is in contact. In addition, the order in which the first electrode 130 and the second electrode 140 are formed may be formed simultaneously or in reverse order. However, the present invention does not limit the formation method or the order of formation of the first electrode 130 and the second electrode 140.

3 is a graph showing a reflectance-wavelength curve of a solar cell according to an embodiment of the present invention, see FIG. 3. The curve L1 represents the reflectance-wavelength curve of the solar cell 100 in which the graphene oxide layer 120 is formed, and the curve L2 represents the reflectance-wavelength curve of the solar cell in which the graphene oxide layer 120 is not formed. As shown in FIG. 3, the reflectance of the curve L1 decreases as the wavelength increases, wherein the reflectance of the curve L1 is lower than the reflectance of the curve L2 as the wavelength increases. As shown in FIG. 3, the anti-reflection performance of the curve L1 in which the graphene oxide layer 120 solar cell 100 is formed is better than the curve L2 in which the graphene oxide layer 120 solar cell is not formed. Therefore, the graphene oxide layer 120 can be used as an antireflection layer In order to reduce the reflectance of the incident light of the solar cell 100, it is possible to increase the incident light that the solar cell 100 can absorb.

4 is a graph showing a voltage-capacitance curve of a metal oxide semiconductor of a graphene oxide layer according to an embodiment of the present invention, see FIG. Curve L3 represents a voltage-capacitance curve for forming a graphene oxide layer 120 on a native yttria-yttrium structure and fabricating an aluminum electrode to form an aluminum-graphene oxide-negative oxide layer-yttrium-aluminum metal oxide semiconductor structure. Curve L4 represents a voltage-capacitance curve of a native yttria-yttrium structure and an aluminum electrode to form an aluminum-primary oxide-yttrium-aluminum metal oxide semiconductor. As shown in FIG. 4, the flat band voltage value of the curve L3 of the metal oxide semiconductor structure in which the graphene oxide layer 120 is formed is compared with the flat band of the curve L4 of the metal oxide semiconductor structure in which the graphene oxide layer 120 is not formed. The voltage value is large, that is, the curve L3 is shifted to the right by the curve L4. Therefore, it is indicated that the graphene oxide layer 120 has a negative oxide layer charge, so that the surface of the substrate 110 of the solar cell 100 can be passivated, which means that the graphene oxide layer 120 can be used as a passivation layer of the solar cell 100, thereby oxidizing graphene. The layer 120 can reduce the electron-hole recombination rate of the surface of the solar cell 100.

Further, the method of manufacturing the solar cell 100 may further include step S104. Referring to FIG. 2 again, in step S104, the graphene oxide layer 120 is used as a mask etching substrate 110 to form a roughness on the surface of the second conductive semiconductor layer 114. Generally, the surface of the substrate 110 is etched to form a rough surface, thereby reducing the ratio of incident light reflection, thereby reducing the loss of reflected light. In the present embodiment, the substrate 110 is etched through the graphene oxide layer 120 using a potassium hydroxide solution as an etching solution. The surface of the substrate 110 after etching is undulated to form a rough structure. When incident light is incident from the end of the graphene oxide layer 120, the graphene oxide layer 120 can be used to reduce the reflectance of incident light. Although the method of manufacturing the solar cell 100 can etch the substrate 110 through the graphene oxide layer 120, the present invention is not limited thereto.

In summary, the method for manufacturing a solar cell according to an embodiment of the present invention is formed. The graphene oxide layer is on the substrate, and the graphene oxide layer is in contact with the second conductive type semiconductor layer. The graphene oxide layer can be used not only as a passivation layer of a solar cell, but also to reduce the electron-hole recombination rate of the surface of the solar cell. The graphene oxide layer can also serve as an anti-reflection layer of the solar cell to reduce the incident light of the solar cell. The reflectivity, thereby increasing the incident light that the solar cell can absorb, thereby improving the photoelectric conversion efficiency of the solar cell. In addition, the graphene oxide layer is formed by immersing the substrate in the graphene oxide suspension solution. Therefore, the process of the graphene oxide layer is relatively simple, and the manufacturing cost of forming the passivation layer and the anti-reflection layer of the solar cell can be reduced.

The above is only an embodiment of the present invention, and is not intended to limit the scope of the invention. It is still within the scope of patent protection of the present invention to make any substitutions and modifications of the modifications made by those skilled in the art without departing from the spirit and scope of the invention.

100‧‧‧ solar cells

110‧‧‧Substrate

112‧‧‧First Conductive Semiconductor Layer

114‧‧‧Second conductive semiconductor layer

120‧‧‧ Graphene oxide layer

130‧‧‧First electrode

140‧‧‧second electrode

Claims (9)

A method of manufacturing a solar cell, comprising: providing a substrate, the substrate comprising a first conductive semiconductor layer and a second conductive semiconductor layer, wherein the first conductive semiconductor layer and the second conductive semiconductor layer are electrically conductive Conversely, forming a graphene oxide layer on the substrate, and the graphene oxide layer is in contact with the second conductive semiconductor layer; and forming a first electrode and a second electrode on the substrate, and the first electrode In contact with the first conductive semiconductor layer, the second electrode is in contact with the second conductive semiconductor layer. The method for producing a solar cell according to claim 1, wherein the graphene oxide layer is formed by immersing the substrate in a graphene oxide suspension solution. The method for manufacturing a solar cell according to claim 2, wherein the method for producing a graphene oxide suspension solution comprises: forming a graphite into graphite oxide; and placing the graphite oxide in a deionized water to form an oxidation. The graphite solution is subjected to a first ultrasonic wave oscillation treatment and a first centrifugation treatment by an ultrasonic oscillator and a centrifuge to form a graphene oxide suspension solution. The method for manufacturing a solar cell according to claim 3, wherein the first ultrasonic oscillation processing time is between 20 and 60 minutes, and the first centrifugal processing speed is between 500 and 15,000 per minute (revolutions per minute) , rpm), the first centrifugation time is between 20 and 60 minutes. The method for manufacturing a solar cell according to claim 4, wherein the graphite oxide suspension solution is further subjected to a second ultrasonic oscillation treatment, wherein the second ultrasonic oscillation treatment time is between 60 and 150 minutes, and then performed. A second centrifugation process is between 500 and 15,000 revolutions per minute (rpm), and the second centrifugation time is between 20 and 60 minutes. The method of manufacturing a solar cell according to claim 1, wherein the substrate is subjected to a surface treatment before forming the graphene oxide layer on the substrate. The method of manufacturing a solar cell according to claim 6, wherein the surface treatment comprises immersing the substrate in an SCl solution. The method for producing a solar cell according to claim 1, wherein the substrate is etched using the graphene oxide layer as a mask to form a rough structure on a surface of the second conductive semiconductor layer. The method for producing a solar cell according to claim 1, wherein the graphene oxide layer is formed by chemical vapor deposition, mechanical peeling, or epitaxial growth.