TWI751681B - Alignment marker of thin film solar cell and manufacturing method thereof - Google Patents

Abstract

A manufacturing method of an alignment marker of a thin film solar cell including steps below is provided. First, a first electrode material layer is formed on a substrate, wherein a surface, away from the substrate, of the first electrode material layer having a plurality of microstructures. Then, a photoelectric conversion layer and a second electrode layer are formed on the first electrode material layer, wherein the photoelectric conversion layer is disposed between the first electrode material layer and the second electrode layer, and an orthographic projection of the first electrode material layer regarding to a normal direction of the substrate is larger than an orthographic projection of the photoelectric conversion layer and the second electrode layer regarding to a normal direction of the substrate. Next, a photoresist layer is formed on the first electrode material layer, wherein the photoresist layer covers a portion of the first electrode material layer, the second electrode layer and the photoelectric conversion layer. After that, an etching process is performed on the first electrode material layer by using the photoresist layer to form a first electrode layer. An alignment marker is also provided.

Description

Alignment mark for thin film solar cell and method for producing the same

The present invention relates to an alignment mark and a manufacturing method thereof, and in particular, to an alignment mark of a thin film solar cell and a manufacturing method thereof.

Referring to FIGS. 3A and 3B , in the manufacturing process of the solar cell, the alignment marks 1 and 2 used for alignment are generally composed of the first electrode layer 1100 and the photoelectric conversion layer 1200 (including the sequential stacking on the substrate 1000 ) The stacked first extrinsic semiconductor layer 1220 , the intrinsic semiconductor layer 1240 , the second extrinsic semiconductor layer 1260 ) and the second electrode layer 1300 are formed. However, in the process of forming the alignment mark, it needs to go through multiple etching processes. During the formation process of the first electrode layer 1100 , the etching process it undergoes will cause itself to be excessively side-etched or cause the second electrode layer that has been formed. 1300 is partially removed, and the resulting problems are shown in Figures 3A and 3B, respectively. In this case, the alignment marks 1 and 2 used for alignment will reduce the accuracy of alignment due to incomplete structures or even peel off the alignment marks 1 and 2 from the substrate 1000 .

The present invention provides a method for manufacturing an alignment mark of a thin-film solar cell, and the produced alignment mark has a complete structure, so that the alignment mark can be used for subsequent alignment with accurate precision. In addition, the alignment mark of the thin-film solar cell provided by the present invention can be simultaneously formed in the process of manufacturing the thin-film solar cell, so there is no need to add a new process.

The manufacturing method of the alignment mark of the thin film solar cell of the present invention includes the following steps. First, a first electrode material layer is formed on a substrate, wherein a surface of the first electrode material layer away from the substrate has a plurality of microstructures. Next, a photoelectric conversion layer and a second electrode layer are formed on the first electrode material layer, wherein the photoelectric conversion layer is disposed between the first electrode material layer and the second electrode layer, and the first electrode material layer is in the normal direction of the substrate The orthographic projection surface of the upper surface is larger than the orthographic projection surface of the second electrode layer and the photoelectric conversion layer in the normal direction of the substrate. Next, a photoresist layer is formed on the first electrode material layer, wherein the photoresist layer covers part of the first electrode material layer, the second electrode layer and the photoelectric conversion layer. Then, an etching process is performed on the first electrode material layer by using the photoresist layer to form a first electrode layer.

In an embodiment of the present invention, the orthographic projection surface of the contact portion between the above-mentioned photoresist layer and part of the first electrode material layer in the normal direction of the substrate has a width of at least greater than 1 μm.

In an embodiment of the present invention, the above-mentioned step of forming the first electrode material layer on the substrate includes performing an etching process.

In an embodiment of the present invention, the above-mentioned etching process for the first electrode material layer includes a wet etching process.

In an embodiment of the present invention, the above-mentioned formation of the photoelectric conversion layer and the second electrode layer on the first electrode material layer includes the following steps. First, a photoelectric conversion material layer is formed on the first electrode material layer. Next, a second electrode material layer is formed on the photoelectric conversion material layer. Next, an etching process is sequentially performed on the second electrode material layer and the photoelectric conversion material layer.

In an embodiment of the present invention, the above-mentioned etching process for the second electrode material layer includes a wet etching process.

In an embodiment of the present invention, the above-mentioned etching process for the photoelectric conversion material layer includes a dry etching process.

In an embodiment of the present invention, the photoresist layer is removed after the first electrode layer is formed.

The present invention provides an alignment mark for a thin film solar cell, which has a complete structure and can be used for subsequent alignment with accurate precision.

The alignment mark of the thin-film solar cell of the present invention includes a first electrode layer, a photoelectric conversion layer and a second electrode layer sequentially arranged on the substrate, wherein the orthographic projection surface of the first electrode layer in the normal direction of the substrate is larger than that of the first electrode layer in the normal direction of the substrate. The orthographic projection plane of the two electrode layers and the photoelectric conversion layer in the normal direction of the substrate.

In an embodiment of the present invention, the orthographic plane of the first electrode layer in the normal direction of the substrate covers the orthographic plane of the second electrode layer and the photoelectric conversion layer in the normal direction of the substrate.

Based on the above, the present invention provides a method for manufacturing an alignment mark of a thin film solar cell by forming a photoresist layer covering a portion of the first electrode material layer and the second electrode layer before performing the etching process on the first electrode material layer, It can avoid partial removal of the second electrode layer or excessive side etching of the first electrode material layer during the subsequent etching process of the first electrode material layer, so that the alignment mark produced has a complete structure and Subsequent use for alignment with accurate precision.

Reference will now be made in detail to the exemplary embodiments of the present invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numerals are used in the drawings and description to refer to the same or like parts. The present invention may also be embodied in various forms and should not be limited to the embodiments described herein. The thicknesses of layers and regions in the drawings are exaggerated for clarity. The same or similar reference numerals denote the same or similar elements, and the detailed description in the following paragraphs will not be repeated. In addition, the directional terms mentioned in the embodiments, such as: up, down, left, right, front or rear, etc., only refer to the directions of the drawings. Accordingly, the directional terms used are illustrative and not limiting of the present invention.

FIG. 1 is a flowchart of a method for manufacturing an alignment mark of a thin film solar cell according to an embodiment of the present invention.

Referring to FIG. 1 , first, a first electrode material layer 110 a is formed on the substrate 100 . The substrate 100 is made of, for example, a transparent material, so that ambient light can penetrate through it and enter the interior of the thin film solar cell. In some embodiments, the material of the substrate 100 includes glass, transparent resin, or other suitable transparent materials. The above-mentioned transparent resin may be, for example, polyethylene terephthalate, polyethylene naphthalate, polycarbonate, polyether or polyimide. In this embodiment, the material of the substrate 100 is glass. The formation method of the first electrode material layer 110a is, for example, comprehensively formed on the substrate by using physical vapor deposition method or chemical vapor deposition method. In some embodiments, the material of the first electrode material layer 110 a includes transparent conductive oxide (Transparent Conductive Oxide; TCO). For example, the material of the first electrode material layer 110a may include indium tin oxide (ITO), aluminum doped zinc oxide (AZO), tin oxide (SnO ₂ ), or indium oxide (In ₂ O ₃ ).

Next, an etching process is performed on the first electrode material layer 110 a to form a first electrode material layer 110 b , wherein a surface of the first electrode material layer 110 b away from the substrate 100 has a plurality of microstructures 112 . The purpose of performing the etching process is to make the surface of the first electrode material layer 110b away from the substrate 100 to have improved surface roughness. Therefore, when ambient light travels to it, it will be scattered by the microstructures 112, and the scattered ambient light will travel The distance will be increased to reach a total reflection condition, thereby increasing the amount of reflected ambient light. In some embodiments, the above-mentioned etching process may include a wet etching process, a dry etching process, or a combination thereof. In this embodiment, a wet etching process is used.

Next, a photoelectric conversion material layer 120a is formed on the first electrode material layer 110b. The formation method of the photoelectric conversion material layer 120a is formed by, for example, chemical vapor deposition, but the present invention is not limited thereto. In some embodiments, the material of the photoelectric conversion material layer 120a may include monocrystalline silicon, polycrystalline silicon or amorphous silicon, that is, the formed thin film solar cell in this embodiment may be a silicon thin film solar cell. In this embodiment, the material of the photoelectric conversion material layer 120a is amorphous silicon. The photoelectric conversion material layer 120a includes, for example, a first extrinsic semiconductor material layer 122a, an intrinsic semiconductor material layer 124a, and a second extrinsic semiconductor material layer 126a that are sequentially stacked, wherein the first extrinsic semiconductor material layer 122a has the first extrinsic semiconductor material layer 122a. a doping type, and the second extrinsic semiconductor material layer 126a has a second doping type. The above-mentioned first doping type and second doping type are each one of P-type and N-type. In this embodiment, the first doping type is P-type, and the second doping type is N-type, but the invention is not limited thereto.

Then, a second electrode material layer 130a is formed on the photoelectric conversion material layer 120a. The formation method of the second electrode material layer 130a is formed by, for example, sputtering or chemical vapor deposition, but the present invention is not limited thereto. The material of the second electrode material layer 130a is, for example, metal, alloy or metal oxide. For example, the material of the second electrode material layer 130a includes molybdenum-tantalum or a combination of molybdenum-tantalum and aluminum.

After that, an etching process is sequentially performed on the second electrode material layer 130 a and the photoelectric conversion material layer 120 a to form the second electrode layer 130 and the photoelectric conversion layer 120 respectively. In some embodiments, the above-mentioned etching process may include a wet etching process, a dry etching process, or a combination thereof. In this embodiment, the etching process for the second electrode material layer 130 a is a wet etching process, and the etching process for the photoelectric conversion material layer 120 a is a dry etching process. In addition, the formed photoelectric conversion layer 120 includes a first extrinsic semiconductor layer 122 , an intrinsic semiconductor layer 124 and a second extrinsic semiconductor layer 126 that are sequentially stacked. In addition, the orthographic projection surface of the first electrode material layer 110 b in the normal direction Z of the substrate 100 is larger than the orthographic projection surfaces of the second electrode layer 130 and the photoelectric conversion layer 120 in the normal direction Z of the substrate 100 . In this embodiment, the orthographic projection surface of the first electrode material layer 110 b on the normal direction Z of the substrate 100 covers the orthographic projection surface of the second electrode layer 130 and the photoelectric conversion layer 120 on the normal direction Z of the substrate 100 , That is, the edge of the orthographic projection surface of the second electrode layer 130 and the photoelectric conversion layer 120 in the normal direction Z of the substrate 100 does not exceed the normal projection surface of the first electrode material layer 110b in the normal direction Z of the substrate 100. edge.

Then, a photoresist layer 200 is formed on the first electrode material layer 110b, wherein the photoresist layer 200 covers part of the first electrode material layer 110b, the second electrode layer 130 and the photoelectric conversion layer 120. In detail, in addition to being formed on the first electrode material layer 110b, the photoresist layer 200 is also formed on the top surface of the second electrode layer 130, the side surface of the second electrode layer 130 and the side surface of the photoelectric conversion layer 120, based on Therefore, when the first electrode material layer 110b is subsequently subjected to the etching process, the photoresist layer 200 is disposed to avoid that part of the second electrode layer 130 is also removed due to the above-mentioned etching process. The photoresist layer 200 includes, for example, an etch-resistant thin film material. In some embodiments, the material of the photoresist layer 200 may include a positive type photoresist material or a negative type photoresist material, which is not particularly limited in the present invention. In the present embodiment, the photoresist layer 200 is in contact with a part of the surface of the first electrode material layer 110 b having the plurality of microstructures 112 , wherein the contact part of the photoresist layer 200 and a part of the first electrode material layer 110 b is on the substrate 100 The orthographic plane of projection in the normal direction Z has a width w of at least greater than 1 micron. In this case, the arrangement of the photoresist layer 200 can avoid excessive side etching of the subsequent first electrode material layer 110b during the etching process.

Finally, an etching process is performed on the first electrode material layer 110b to form the first electrode layer 110, and the photoresist layer 200 is subsequently removed. In some embodiments, the above-mentioned etching process may include a wet etching process, a dry etching process, or a combination thereof. In this embodiment, the etching process for the first electrode material layer 110b is a wet etching process. Since the photoresist layer 200 is provided in the foregoing steps, part of the second electrode layer 130 can be prevented from being removed, and the formed first electrode layer 110 has a complete structure. In this embodiment, the portion of the first electrode layer 110 exposed by the second electrode layer 130 in the normal direction Z of the substrate 100 has a width W of at least greater than 1 μm.

So far, the fabrication of the alignment mark 10 of the thin film solar cell of the present embodiment is completed.

Although the method of manufacturing the alignment mark 10 of the thin film solar cell of the present embodiment is described by taking the above method as an example, the method of forming the alignment mark of the thin film solar cell of the present invention is not limited thereto.

Based on the above, the method for manufacturing an alignment mark for a thin film solar cell of the present embodiment is to form a photoresist layer covering a portion of the first electrode material layer and the second electrode layer before performing the etching process on the first electrode material layer. To avoid partial removal of the second electrode layer or excessive side etching of the first electrode material layer when the subsequent first electrode material layer undergoes an etching process.

Please continue to refer to FIG. 1 , which is a schematic partial cross-sectional view of the alignment mark 10 of the thin film solar cell shown in the final step shown in FIG. 1 . The alignment mark 10 of the thin film solar cell according to the embodiment of the present invention includes a first electrode layer 110 , a photoelectric conversion layer 120 and a second electrode layer 130 , wherein the first electrode layer 110 , the photoelectric conversion layer 120 and the second electrode layer 130 are in sequence arranged on the substrate 100 . The materials and functions of the substrate 100 , the first electrode layer 110 , the photoelectric conversion layer 120 and the second electrode layer 130 can be referred to the above-mentioned embodiments, and details are not repeated here. In some embodiments, the photoelectric conversion layer 120 includes a first extrinsic semiconductor layer 122 , an intrinsic semiconductor layer 124 and a second extrinsic semiconductor layer 126 stacked in sequence, wherein the first extrinsic semiconductor layer 122 and the second extrinsic semiconductor layer 126 The doping type of the two extrinsic semiconductor layers 126 can be referred to the above-mentioned embodiments, and details are not described herein again. In this embodiment, the portion of the first electrode layer 110 exposed by the second electrode layer 130 in the normal direction Z of the substrate 100 has a minimum width W, wherein the minimum width W is at least greater than 1 micrometer. In addition, the orthographic plane of the first electrode layer 110 in the normal direction Z of the substrate 100 is larger than the orthographic plane of the second electrode layer 130 and the photoelectric conversion layer 120 in the normal direction Z of the substrate 100 . In this embodiment, the orthographic plane of the first electrode layer 110 on the normal direction Z of the substrate 100 covers the orthographic plane of the second electrode layer 130 and the photoelectric conversion layer 120 on the normal direction Z of the substrate 100 , that is, , the edge of the orthographic plane of the second electrode layer 130 and the photoelectric conversion layer 120 in the normal direction Z of the substrate 100 does not exceed the edge of the orthographic plane of the first electrode layer 110 in the normal direction Z of the substrate 100 . Based on this, the alignment mark 10 of the thin film solar cell of the present invention can have a stable base, which can prevent the alignment mark 10 from being peeled off from the substrate 100 to have good alignment accuracy.

Please refer to FIG. 2A . FIG. 2A is a schematic top view of a partial top view of an alignment mark of a thin film solar cell according to an embodiment of the present invention.

In the alignment mark 10 a of the thin film solar cell shown in FIG. 2A , the orthographic projection of the second electrode layer 130 on the normal direction Z of the substrate 100 is a cross, but the invention is not limited thereto. As shown in FIG. 2A , the second electrode layer 130 is composed of a first rectangle 130_a and two second rectangles 130_b, wherein the two second rectangles 130_b are respectively located on opposite sides of the first rectangle 130_a and are opposite to the first rectangle 130a get in touch with. The first rectangle 130_a has, for example, a length of 0.005˜10 mm and a width of 0.005˜10 mm. In this embodiment, the first rectangle 130_a has a length of 0.05 mm and a width of 0.01 mm. The second rectangle 130_b has, for example, a length of 0.005˜10 mm and a width of 0.005˜10 mm. In this embodiment, the second rectangle 130_b has a length of 0.02 mm and a width of 0.01 mm. In addition, in FIG. 2A , the orthographic projection of the first electrode layer 110 on the normal direction Z of the substrate 100 is a square, but the present invention is not limited to this. The orthographic projection of the first electrode layer 110 on the normal direction Z of the substrate 100 has, for example, a side length of 0.01-10 mm. In this embodiment, the orthographic projection of the first electrode layer 110 on the normal direction Z of the substrate 100 has a side length of 1 mm. In some embodiments, the portion of the first electrode layer 110 exposed by the second electrode layer 130 in the normal direction Z of the substrate 100 has a minimum width W1, wherein the minimum width W1 is at least greater than 1 micrometer.

Please refer to FIG. 2B . FIG. 2B illustrates a partial top view of an alignment mark of a thin film solar cell according to another embodiment of the present invention.

In the alignment mark 10b of the thin film solar cell shown in FIG. 2B , the orthographic projection of the second electrode layer 130 on the normal direction Z of the substrate 100 is a combination of a cross and four rectangles, but the present invention does not use this limited. As shown in FIG. 2B , the cross-shaped projection of the second electrode layer 130 is composed of a third rectangle 130_c and two fourth rectangles 130_d, wherein the two fourth rectangles 130_d are respectively located on opposite sides of the third rectangle 130_c and Contact with the third rectangle 130_c. The four rectangular projections of the second electrode layer 130 are composed of four fifth rectangles 130_e. The fifth rectangles 130_e are located in the four regions divided by the cross-shaped projections, and each has a specific relationship with the cross-shaped projections. interval. The third rectangle 130_c has, for example, a length of 0.005˜10 mm and a width of 0.005˜10 mm. In this embodiment, the third rectangle 130_c has a length of 0.05 mm and a width of 0.01 mm. The fourth rectangle 130_d has, for example, a length of 0.005˜10 mm and a width of 0.005˜10 mm. In this embodiment, the fourth rectangle 130_d has a length of 0.02 mm and a width of 0.01 mm. The fifth rectangle 130_e has, for example, a length of 0.0025˜5 mm and a width of 0.0025˜5 mm. In this embodiment, the fifth rectangle 130_e has a length of 0.05 mm and a width of 0.01 mm. In addition, in FIG. 2B , the orthographic projection of the first electrode layer 110 on the normal direction Z of the substrate 100 is a square, but the present invention is not limited to this. The orthographic projection of the first electrode layer 110 on the normal direction Z of the substrate 100 has, for example, a side length of 0.01-10 mm. In this embodiment, the orthographic projection of the first electrode layer 110 on the normal direction Z of the substrate 100 has a side length of 0.07 mm. In some embodiments, the portion of the first electrode layer 110 exposed by the second electrode layer 130 in the normal direction Z of the substrate 100 has a minimum width W2, wherein the minimum width W2 is at least greater than 1 micrometer.

Please refer to FIG. 2C . FIG. 2C shows a modified embodiment of the partial top view of the alignment mark of the thin film solar cell shown in FIG. 2A .

The main difference between the alignment mark 10c of the thin film solar cell shown in FIG. 2C and the alignment mark 10a of the thin film solar cell shown in FIG. 2A is that the orthographic projection of the first electrode layer 110 on the normal direction Z of the substrate 100 is also for the cruciform. In this embodiment, the portions of the first electrode layer 110 exposed by the second electrode layer 130 in the normal direction Z of the substrate 100 all have substantially the same width W3, wherein the minimum width W3 is at least greater than 1 μm.

To sum up, the method for manufacturing the alignment mark of the thin film solar cell provided by the present invention is to form a photoresist covering a portion of the first electrode material layer and the second electrode layer before performing the etching process on the first electrode material layer. layer, which can avoid partial removal of the second electrode layer or excessive side etching of the first electrode material layer when the subsequent first electrode material layer undergoes an etching process, thereby enabling the alignment mark to have a complete structure. This enables accurate precision for subsequent use in alignment. In addition, the alignment mark of the thin-film solar cell provided by the present invention can be simultaneously formed during the process of manufacturing the thin-film solar cell, so there is no need to add a new process, and the manufacturing cost of the alignment mark can be reduced.

Furthermore, in the alignment mark of the thin film solar cell provided by the present invention, the portion of the first electrode layer exposed by the second electrode layer in the normal direction of the substrate has a minimum width, wherein the minimum width is at least greater than 1 micron. Based on this, the alignment mark of the thin film solar cell of the present invention can have a stable base, which can avoid peeling of the alignment mark from the substrate to have good alignment accuracy.

1, 2, 10: alignment mark 100, 1000: substrate 110, 1100: the first electrode layer 110a, 110b: first electrode material layer 112: Microstructure 120, 1200: Photoelectric conversion layer 120a: Photoelectric conversion material layer 122: the first extrinsic semiconductor layer 122a: the first extrinsic semiconductor material layer 124: Intrinsic semiconductor layer 124a: Intrinsic semiconductor material layer 126: the second extrinsic semiconductor layer 126a: the second extrinsic semiconductor material layer 130, 1300: the second electrode layer 130a: second electrode material layer 130_a: first rectangle 130_b: Second rectangle 130_c: Third rectangle 130_d: Fourth rectangle 130_e: Fifth rectangle 200: photoresist layer w, W, W1, W2, W3: width Z: normal direction

FIG. 1 is a flowchart of a method for manufacturing an alignment mark of a thin film solar cell according to an embodiment of the present invention. FIG. 2A is a partial top schematic view of an alignment mark of a thin film solar cell according to an embodiment of the present invention. FIG. 2B is a partial top schematic view of an alignment mark of a thin film solar cell according to another embodiment of the present invention. FIG. 2C shows a modified example of a partial top view of the alignment mark of the thin film solar cell shown in FIG. 2A . 3A and 3B are schematic partial cross-sectional views of alignment marks of a conventional thin-film solar cell.

10: Alignment mark

100: Substrate

110: the first electrode layer

110a, 110b: first electrode material layer

112: Microstructure

120: Photoelectric conversion layer

120a: Photoelectric conversion material layer

122: the first extrinsic semiconductor layer

122a: the first extrinsic semiconductor material layer

124: Intrinsic semiconductor layer

124a: Intrinsic semiconductor material layer

126: the second extrinsic semiconductor layer

126a: the second extrinsic semiconductor material layer

130: the second electrode layer

130a: second electrode material layer

200: photoresist layer

w, W: width

Z: normal direction

Claims (10)

A method for manufacturing an alignment mark of a thin film solar cell, comprising: forming a first electrode material layer on a substrate, wherein the surface of the first electrode material layer away from the substrate has a plurality of microstructures; A photoelectric conversion layer and a second electrode layer are formed on the electrode material layer, wherein the photoelectric conversion layer is arranged between the first electrode material layer and the second electrode layer, and the first electrode material layer is in the The orthographic projection surface in the normal direction of the substrate is larger than the orthographic projection surface of the second electrode layer and the photoelectric conversion layer in the normal direction of the substrate; the light is formed on the first electrode material layer A resist layer, wherein the photoresist layer covers part of the first electrode material layer, the second electrode layer and the photoelectric conversion layer; and the first electrode material layer is etched by using the photoresist layer process to form the first electrode layer. The method for manufacturing an alignment mark of a thin film solar cell according to claim 1, wherein a contact portion of the photoresist layer and a portion of the first electrode material layer is in a positive direction in the normal direction of the substrate. The projection surface has a width of at least greater than 1 micron. The method for manufacturing an alignment mark of a thin film solar cell according to claim 1, wherein the step of forming the first electrode material layer on the substrate includes performing an etching process. The method for manufacturing an alignment mark of a thin film solar cell according to claim 3, wherein the etching process performed on the first electrode material layer includes a wet etching process. The method for manufacturing an alignment mark for a thin film solar cell according to claim 1, wherein the step of forming the photoelectric conversion layer and the second electrode layer on the first electrode material layer includes: forming a photoelectric conversion material layer on an electrode material layer: forming a second electrode material layer on the photoelectric conversion material layer; and sequentially performing an etching process on the second electrode material layer and the photoelectric conversion material layer. The method for manufacturing an alignment mark of a thin film solar cell according to claim 5, wherein the etching process performed on the second electrode material layer includes a wet etching process. The method for manufacturing an alignment mark of a thin film solar cell according to claim 5, wherein the etching process performed on the photoelectric conversion material layer includes a dry etching process. The method for manufacturing an alignment mark of a thin film solar cell according to claim 1, wherein after forming the first electrode layer, the photoresist layer is removed. An alignment mark for a thin film solar cell, comprising a first electrode layer, a photoelectric conversion layer and a second electrode layer sequentially arranged on a substrate, wherein the orthographic projection of the first electrode layer on the normal direction of the substrate The surface is larger than the orthographic projection surface of the second electrode layer and the photoelectric conversion layer in the normal direction of the substrate, The orthographic projection surface of the second electrode layer in the normal direction of the substrate includes at least a cross-shaped pattern, wherein the first electrode layer is surrounded by the normal direction of the substrate. The exposed portions of the second electrode layer have substantially the same width, and the width is at least greater than 1 micrometer. The alignment mark for thin film solar cells according to claim 9, wherein the orthographic projection surface of the first electrode layer in the normal direction of the substrate covers the second electrode layer and the photovoltaic the orthographic projection plane of the conversion layer in the normal direction of the substrate.

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