TWI648863B - Solar cell and a manufacturing method thereof - Google Patents

Abstract

A solar cell comprising a first conductive semiconductor substrate, an emitter diffusion layer, a passivation layer, an antireflection layer, a second metal electrode, a thin oxygen layer, a crystalline layer, an insulating layer, a metal layer, and a patterned metal. The emitter diffusion layer is disposed adjacent to the front side of the substrate. The passivation layer is disposed adjacent to the emitter diffusion layer. The anti-reflective layer is disposed adjacent to the passivation layer. The second metal electrode is disposed adjacent to the anti-reflective layer, and the thin oxygen layer is disposed adjacent to the lower surface of the substrate. The crystal layer is disposed adjacent to the thin oxygen layer, and the insulating layer is disposed adjacent to the crystal layer. The metal layer is placed next to the insulating layer. The patterned metal on the insulating layer contacts the crystalline layer and penetrates the metal layer.

Description

Solar cell and method of manufacturing same

The disclosure is directed to a solar cell, and more particularly to the manufacture of a solar cell.

Nowadays, environmental awareness in society has risen and oil energy has fallen sharply. Countries are scrambling to discover new energy sources to solve environmental pollution and energy crisis. Among them, the energy required for solar cells is the easiest to obtain, which has led researchers in various countries to study how to effectively use solar power to solve the energy crisis.

The main issue of solar cells is how to absorb more light. The traditional solar cell architecture uses a full-face silver paste on the back side of the battery. This can reduce the series resistance and increase the amount of reflection of long-wave light on the back of the battery, but the disadvantage is that the silver paste on the entire surface is too expensive. And the manufacturing equipment and technology are not mature enough.

Therefore, how to reduce the cost of the solar cell without reducing the efficiency of converting the light energy into electrical energy is the problem to be solved by the present invention.

In order to solve the above problems, one aspect of the case is to provide a Solar battery. The solar cell comprises a substrate, an emitter diffusion layer disposed adjacent to an upper surface of the substrate, a passivation layer disposed adjacent to the emitter diffusion layer, an anti-reflection layer disposed adjacent to the passivation layer, a second metal electrode disposed adjacent to the anti-reflection layer, and disposed adjacent to each other A thin oxygen layer on the lower surface of the substrate, a crystal layer disposed adjacent to the thin oxygen layer, an insulating layer disposed adjacent to the crystal layer, a metal layer disposed adjacent to the insulating layer, and a patterned metal.

Another aspect of the present invention is to provide a method for fabricating a solar cell, which basically consists of: (a) providing a substrate; (b) engraving the surface of the substrate into a pyramid; (c) performing boron diffusion on the upper surface An emitter diffusion layer; (d) performing boric acid glass removal; (e) forming a thin oxygen layer on the lower surface of the substrate; (f) depositing a passivation layer on the emitter diffusion layer; (g) depositing an anti-deposition on the passivation layer a reflective layer; (h) performing microcrystalline phosphorus diffusion deposition on the thin oxygen layer to form a crystalline layer; (i) depositing an insulating layer on the crystalline layer; (j) printing a plurality of second metal electrodes on the anti-reflective layer; Opening a plurality of via holes in the insulating layer and spacing the via holes from each other and exposing a portion of the crystal layer; (1) printing a patterned metal and the patterned metal comprising a plurality of first metal electrodes respectively located in the through holes And (m) printing a metal layer on the insulating layer and the patterned metal, and the two ends of the first metal electrodes are electrically connected to the crystal layer and the metal layer, respectively.

100‧‧‧ solar cells

110‧‧‧Substrate

120‧‧‧ upper surface

121‧‧ ‧ emitter diffusion layer

122‧‧‧ Passivation layer

123‧‧‧Anti-reflective layer

124‧‧‧Second metal electrode

125‧‧‧Boric acid glass

130‧‧‧lower surface

131‧‧‧Oxygen layer

132‧‧‧ Crystallization layer

133‧‧‧Insulation

134‧‧‧metal layer

135‧‧‧ patterned metal

136‧‧‧First metal electrode

300‧‧‧Methods for manufacturing solar cells

Steps S301, S302, S303, S304, S305, S306, S307, S308, S309, S310, S311, S312, S313‧‧

The aspects of the present disclosure will be better understood from the following detailed description. It should be noted that the various features are not drawn to scale in accordance with standard practice in the industry. In fact, for the sake of clarity, The size of each feature can be arbitrarily increased or decreased.

1 is a schematic structural view of a solar cell according to some embodiments of the present invention; FIG. 2A is a top view of a patterned metal of a solar cell according to some embodiments of the present invention; FIG. 2B is a view according to the present invention A top view of a patterned metal of another solar cell illustrated in some embodiments; FIG. 3 is a flow chart of a solar manufacturing method according to some embodiments of the present invention; and FIGS. 4A-4M are some implementations according to the present invention A schematic cross-sectional view of a solar cell is illustrated.

The relative terms used in the text, such as "bottom" or "bottom" and "upper" or "top", are used to describe the relationship of one element to another in the figures. Relative vocabulary is used to describe different orientations of the device other than those described in the drawings. For example, if the device in one of the figures is turned over, the elements will be described as being located on the "lower" side of the other elements. The exemplary vocabulary "below" may include both "lower" and "upper" orientations depending on the particular orientation of the drawings. Similarly, if the device in one of the figures is turned over, the element will be described as being "below" or "below" the other elements. The exemplary vocabulary "below" or "below" can include both "upper" and "upper" orientations.

When an element is referred to as "on", it can generally mean that the element is directly on the other element, or that other element is present in the two. Conversely, when an element is referred to as being "directly on" another element, it cannot be. As used herein, the term "and/or" encompasses any combination of one or more of the listed associated items.

Referring to FIG. 1 , FIG. 1 is a schematic structural view of a solar cell 100 according to some embodiments of the present disclosure. The solar cell 100 includes a substrate 110, an emitter diffusion layer 121, a passivation layer 122, an anti-reflection layer 123, a second metal electrode 124, a thin oxygen layer 131, a crystal layer 132, an insulating layer 133, a metal layer 134, and a patterned metal 135.

In the present embodiment, the substrate 110 is an N-type germanium substrate, but other types of semiconductor substrates are also within the scope of the present disclosure. The upper surface 120 is the front side of the substrate 110. The upper surface 120 has an emitter diffusion layer 121, a passivation layer 122, an anti-reflection layer 123, and a second metal electrode 124.

The emitter diffusion layer 121 is disposed in close proximity to the upper surface of the substrate 110. In the present embodiment, the emitter diffusion layer 121 is doped with boron, but other trivalent metal dopants are also within the scope of the present disclosure.

The passivation layer 122 is disposed in close proximity to the emitter diffusion layer 121. In the present embodiment, the material of the passivation layer 122 is alumina, but other materials are also within the scope of the present disclosure.

The anti-reflection layer 123 is disposed in close proximity to the passivation layer 122. In the present embodiment, the material of the anti-reflection layer 123 is tantalum nitride, but other materials are also within the scope of the present disclosure.

In this embodiment, the emitter diffusion layer 121 and the passivation layer 122 The shape of the pyramid and the anti-reflection layer 123 is such that the light is not easily reflected out to facilitate the absorption of light. Other arrangements that facilitate the absorption of unsmooth shapes of light are also within the scope of the present disclosure.

The second metal electrode 124 is disposed adjacent to the emitter diffusion layer 121 and penetrates the passivation layer 122 and the anti-reflection layer 123. In the present embodiment, the material of the second metal electrode 124 is silver aluminum, but other materials are also within the scope protected by the present disclosure.

The lower surface 130 is the back surface of the substrate 110. The lower surface 130 has a thin oxygen layer 131, a crystal layer 132, an insulating layer 133, a metal layer 134, and a patterned metal 135.

The thin oxygen layer 131 is disposed adjacent to the lower surface 130 of the substrate 110.

The crystal layer 132 is disposed in close proximity to the thin oxygen layer 131. In the present embodiment, the crystal layer 132 is a crystalline layer diffused by phosphorus, but other materials are also within the scope of the present disclosure.

The insulating layer 133 is disposed in close proximity to the crystalline layer 132. In the present embodiment, the insulating layer 133 may be cerium oxide (SiO ₂ ) or cerium nitride (Si ₃ N ₄ ), but other materials that can be used to passivate the surface are also within the scope of the present disclosure. The insulating layer 133 is used to avoid contact between the P+ type and the N type.

The metal layer 134 is disposed in close proximity to the insulating layer 133. In the present embodiment, the metal layer 134 is made of aluminum, but other metals that can be used for reflection and conduction are also within the scope of the present disclosure.

The patterned metal 135 is located on the insulating layer 133, contacts the crystalline layer 132, and penetrates the metal layer 134. If the patterned metal 135 does not penetrate the metal layer 134, the resistance value will be too high, resulting in poor conductivity. In this embodiment, The patterned metal 135 is lead-containing silver, but other materials are also within the scope of this disclosure. In practical applications, the patterned metal 135 may be a silver paste. Generally, the use of silver glue in the process is relatively expensive. Traditionally, if the silver paste is completely coated on the lower surface 130 of the substrate 110, the effect of conducting and reflecting light can be achieved, but at the same time, the manufacturing cost of the solar cell will be improved.

The patterned metal 135 has a plurality of first metal electrodes 136, which may be in a dot arrangement (such as FIG. 2A), a strip arrangement (such as FIG. 2B), or any pattern arrangement in the present disclosure. Among the protected areas. The plurality of first metal electrodes 136 may be connected to the bus electrodes but may not be connected to each other or may be connected to the bus electrodes. The reason why the above connection to the bus electrode is still conductive is that the patterned metal 135 penetrates the metal layer 134, and the metal layer 134 can be turned on.

2A and 2B are schematic views of the patterned metal 135. An important parameter affecting the arrangement design of the plurality of first metal electrodes 136 in the patterned metal 135 is the area ratio of the patterned metal to the metal layer. If the area ratio is too large, the load on the lower surface is increased, and the life of the solar cell is reduced, and the area ratio is too large. A small increase in resistance reduces the efficiency of the solar cell. Thus, in some embodiments, the area ratio of patterned metal 135 relative to the total area of metal layer 134 is set to be from about 0.2% to about 1%. Since the area ratio is about 0.2% to about 1%, if silver paste is used to manufacture the patterned metal 135, the patterned metal 135 formed in the present invention has a silver paste amount saved compared to the conventional method of manufacturing the completely coated silver paste. 85.7% to 95.6%.

Referring to FIG. 2A, FIG. 2A is a top view of the arrangement of the patterned metal 135 of a solar cell according to some embodiments of the present disclosure.

In an embodiment of the present disclosure, FIG. 2A is a patterned metal 135 arranged in a dot shape including a plurality of dot-shaped first metal electrodes 136. The area ratio of all the first metal electrodes 136 to the metal layer 134 is about 0.2% to about 1%.

Referring to FIG. 2B, FIG. 2B is a top view of the arrangement of patterned metal 135 of another solar cell, according to some embodiments of the present disclosure.

In an embodiment of the present disclosure, FIG. 2B is a linearly patterned patterned metal 135 including a plurality of linear first metal electrodes 136. The area ratio of all the first metal electrodes 136 to the metal layer 134 is about 0.2% to about 1%.

Please refer to FIG. 3 and FIGS. 4A-4M, and FIG. 3 is a flow chart of a method 300 for fabricating a solar cell according to an embodiment of the present disclosure. 4A to 4M are schematic cross-sectional views of the solar cell 100 formed according to the manufacturing method 300 shown in FIG. 3 according to different steps. The manufacturing method of the solar cell of the present embodiment basically consists of the following steps, and the phrase "consisting essentially of the following steps" means that the method provided in the embodiment is in addition to the steps mentioned below. In addition, conventional process steps such as handling and cleaning are not excluded, and are described first.

As shown in FIG. 3 and FIG. 4A, step S301 is to provide a substrate. 4A is an embodiment of step S301, providing an N-type semiconductor substrate 110 having an upper surface 120 and a lower surface 130. In general, the upper surface is for receiving sunlight, and the upper surface 120 and the lower surface 130 are opposite side surfaces of the substrate 110.

As shown in FIGS. 3 and 4B, step S302 is to roughen the upper surface 120 of the substrate 110. 4B is an embodiment of step S302, which uses alkali etching to roughen the upper surface 120 of the substrate 110, thereby forming a pyramid-like structure on the upper surface 120. In general, the quality of surface roughening mainly depends on the cleanliness of the substrate 110, the concentration and ratio of the etching solution, the temperature of the etching solution, and the reaction time. The purpose of roughening the upper surface 120 of the substrate 110 is to increase the light receiving rate to prevent the light from being directly reflected by the smooth upper surface 120.

As shown in FIG. 3 and FIG. 4C, step S303 is to perform boron diffusion on the substrate 110. 4C graph of step S303 one embodiment, boron diffusion using gas containing boron, for example, B ₂ H ₆ plus oxygen gas is diffused in high temperature diffusion furnace tube. After the boron ion diffusion is completed, the boron ions contained in the gas diffuse into the upper surface 120 of the substrate 110 to form a P-type emitter diffusion layer 121. The diffusion depth of boron ion diffusion is determined by the concentration of boron in the gas, the flow rate of the gas, the reaction time, and the temperature of the tube. While the boron ion is diffused, the twinned surface of the semiconductor substrate 110 reacts with oxygen or moisture in the air, especially the thermal oxidation effect caused by the heating, so that boric acid glass is formed on the upper surface 120 of the substrate 110 of the solar cell 100. 125.

In step S303, boron is used as a P-type material, and N-type germanium crystal cells are doped in a high-temperature furnace tube to form a P-N junction. Light can be generated by passing the light through the P-N interface in the solar cell 100. In the present embodiment, boron is used as the P-type material, but other trivalent metal materials are also within the scope of the present disclosure.

As shown in FIG. 3 and FIG. 4D, step S304 is performed for boron. Removal of acid glass 125. 4D is an embodiment of step S304, in which the substrate 110 of the solar cell 100 is immersed in an acidic solution to dissolve the boric acid glass 125 on the upper surface 120 of the substrate 110.

As shown in FIGS. 3 and 4E, step S305 is to form a thin oxygen layer 131 on the lower surface 130 of the substrate 110. 4E is an embodiment of step S305 in which a thin oxygen layer 131 is formed on the lower surface 130 of the substrate 110 of the solar cell 100 using a high temperature nitric acid or ozone process. Any other material that can form the thin oxygen layer 131 on the lower surface 130 of the panel 110 of the solar cell 100 is within the scope of the present disclosure.

As shown in FIG. 3 and FIG. 4F, step S306 is to form a passivation layer 122 on the emitter diffusion layer 121. 4F is an embodiment of step S306, in which an alumina deposition is performed on the P-type emitter diffusion layer 121 of the solar cell 100, and an alumina passivation layer 122 is used in the P-type emitter diffusion layer 121, which not only does not form an inverse The transfer layer causes leakage, which in turn increases the multi-sub-concentration of the P-type emitter diffusion layer 121, reducing the minority concentration, thereby reducing the surface recombination rate. In the present embodiment, alumina is used as the passivation layer 122 for deposition, but other materials that can be deposited as the passivation layer 122 are also within the scope of the present disclosure.

As shown in FIG. 3 and FIG. 4G, step S307 is to form an anti-reflection layer 123 on the passivation layer 122. FIG. 4G is an embodiment of step S307, in which the passivation layer 122 of the solar cell 100 is deposited with a tantalum nitride anti-reflective layer 123. This step is to deposit a layer of tantalum nitride on the passivation layer 122 of the solar cell 100 by chemical deposition to reduce the reflectance of light. In the present embodiment, germanium nitride is deposited and used as the anti-reflective layer 123, but other materials which can be deposited as the anti-reflective layer 123 are also within the scope of the present disclosure.

As shown in FIG. 3 and FIG. 4H, step S308 is to form a crystal layer by performing microcrystalline phosphorus diffusion deposition on the thin oxygen layer. 4H is an embodiment of step S308, in which the thin oxygen layer 131 of the solar cell 100 is subjected to microcrystalline phosphorus diffusion deposition to deposit a crystal layer 132 on the thin oxygen layer 131.

As shown in FIG. 3 and FIG. 4I, step S309 is to form an insulating layer 133 on the crystal layer 132. 4G is an embodiment of step S309, in which the crystal layer 132 of the solar cell 100 is deposited with an insulating layer 133 such as ruthenium or tantalum nitride. The insulating layer 133 is deposited so that the crystalline layer 132 does not contact the metal layer 134. If the crystalline layer 132 contacts the metal layer 134, the electrical conductivity of the metal layer is induced to cause the crystalline layer 132 to form defects. In the present embodiment, the material of the insulating layer 133 may be ceria or tantalum nitride, but other materials which can be deposited as the insulating layer 133 are also within the scope of the present disclosure.

As shown in FIG. 3 and FIG. 4J, step S310 is to print a plurality of second metal electrodes 124 on the anti-reflection layer 123. FIG. 4J is an embodiment of step S310 for performing front electrode printing on the solar cell 100. This step is to print silver aluminum on the second metal electrode 124 by screen printing, and other metals that can be used in the second metal electrode 124 are also within the scope of the present disclosure.

As shown in FIG. 3 and FIG. 4K, step S311 is to open a plurality of through holes in the insulating layer and the through holes are spaced apart from each other and expose a portion of the crystal layer. 4K is an embodiment of step S311 in which a plurality of through holes are formed in the insulating layer 133 of the solar cell 100, and the through holes are spaced apart from each other and expose a portion of the crystal layer 132. In this embodiment, the arrangement of the through holes It is a dot arrangement as shown in FIG. 2A, and other different sizes and arrangements, such as the strip arrangement shown in FIG. 2B, and the area ratio of the metal layer 134 is about 0.2% to 1%, also in the present disclosure. Among the scope protected by the document.

As shown in FIGS. 3 and 4L, step S312 is to print the patterned metal 135, and the patterned metal 135 includes a plurality of first metal electrodes 136 respectively located in those through holes. 4L is an embodiment of step S312 in which the patterned metal 135 is printed on the insulating layer 133 of the solar cell 100, and the patterned metal 135 includes a plurality of first metal electrodes 136. This step is to apply the plurality of first metal electrodes 136 to the plurality of through holes of the insulating layer 133 in a given size and arrangement by screen printing. In the present embodiment, the material of the first metal electrode 136 is lead-containing silver paste, and the method for forming the lead-containing silver paste is a printing method, an inkjet coating method or other suitable methods.

As shown in FIG. 3 and FIG. 4M, in step S313, the metal layer 134 is printed on the insulating layer 133 and the patterned metal 135. 4M is an embodiment of step S313. In the solar cell 100, two ends of the plurality of first metal electrodes 136 of the patterned metal 135 are electrically connected to the crystal layer 132 and the metal layer 134, respectively. In the present embodiment, the metal layer 134 is made of aluminum, but other conductive and reflective metals are also within the scope of the present disclosure.

In summary, the solar cell and the method of manufacturing the same provided by the present invention can use very low cost and utilize light efficiently. In this way, a highly efficient solar cell can be made.

Although the present invention has been disclosed in the above embodiments, it is not intended to limit the case, and any person skilled in the art, without departing from the spirit and scope of the case, Various changes and refinements may be made, so the scope of protection of this case is subject to the definition of the scope of the patent application attached.

Claims (9)

A solar cell comprising: a substrate; a thin oxygen layer disposed adjacent to a lower surface of the substrate; a crystalline layer disposed adjacent to the thin oxygen layer; an insulating layer disposed adjacent to the crystalline layer; a metal layer disposed adjacent to the An insulating layer; and a patterned metal comprising a plurality of first metal electrodes, the first metal electrodes being spaced apart from each other and embedded in the first insulating layer, the two ends of the first metal electrodes being electrically connected to the crystal a layer and the metal layer; wherein the material of the first metal electrodes is different from the material of the metal layer, and an area ratio of the patterned metal to the metal layer is 0.2% to 1%. The solar cell of claim 1, further comprising: an emitter diffusion layer disposed adjacent to an upper surface of the substrate; a passivation layer disposed adjacent to the emitter diffusion layer; and an anti-reflection layer disposed adjacent to the passivation layer And a plurality of second metal electrodes disposed on the anti-reflection layer. The solar cell of claim 2, wherein the emitter diffusion layer is doped with boron. The solar cell of claim 2, wherein the material of the passivation layer is aluminum oxide, the material of the anti-reflection layer is tantalum nitride, and the passivation layer and the anti-reflection layer have a pyramid shape. The solar cell of claim 1, wherein the metal layer is made of aluminum. The solar cell of claim 1, wherein the insulating layer is made of hafnium oxide or tantalum nitride. The solar cell of claim 1, wherein the first metal electrode is made of lead-containing silver paste. A method for manufacturing a solar cell, comprising: providing a substrate; forming a thin oxygen layer on a lower surface of the substrate; performing microcrystalline phosphorus diffusion deposition on the thin oxygen layer to form a crystal layer; and depositing an insulating layer on the crystal layer Opening a plurality of through holes in the insulating layer, the through holes are spaced apart from each other and exposing a portion of the crystal layer; printing a patterned metal, wherein the patterned metal comprises a plurality of first metal electrodes respectively located in the through holes Printing a metal layer on the insulating layer and the patterned metal, the two ends of the first metal electrodes are electrically connected to the crystal layer and the metal layer respectively; wherein the materials of the first metal electrodes and the metal The material of the layers is different, and the area ratio of the patterned metal to the metal layer is 0.2% to 1%. The method for manufacturing a solar cell according to claim 8, comprising: engraving the surface of the substrate into a pyramid shape; performing diffusion of boron on the upper surface to form an emitter diffusion layer; performing removal of boric acid glass; and depositing on the emitter diffusion layer a passivation layer; depositing an anti-reflective layer on the passivation layer; and printing a plurality of second metal electrodes on the anti-reflective layer.