WO2020015169A1

WO2020015169A1 - Solar cell and preparation method therefor

Info

Publication number: WO2020015169A1
Application number: PCT/CN2018/107723
Authority: WO
Inventors: 白安琪; 王雪戈
Original assignee: 北京铂阳顶荣光伏科技有限公司
Priority date: 2018-07-19
Filing date: 2018-09-26
Publication date: 2020-01-23
Also published as: CN108649080A

Abstract

The present disclosure relates to a solar cell and a preparation method therefor, and relates to the technical field of solar cells. The solar cell is designed for improving photoelectric conversion efficiency. The solar cell comprises a base substrate; a back electrode layer, a light-absorbing layer, a buffer layer and a window layer are stacked on the base substrate successively in a direction away from said base substrate. The contact surface between the back electrode layer and the light-absorbing layer is a three-dimensional structure. The present solar cell and preparation method therefor improve the photoelectric conversion efficiency of solar cells.

Description

Solar cell and preparation method thereof

Technical field

The present disclosure relates to the technical field of solar cells, and in particular, to a solar cell and a method for preparing the same.

Background technique

Compared with general crystalline silicon solar cells, thin film solar cells have the advantages of good flexibility, high power generation, excellent low-light performance and high-temperature performance, and light weight. Among them, CIS (copper indium tin) based thin-film solar cells have a wider application range.

At present, a typical preparation method of a CIS-based thin-film solar cell is as follows: firstly, a uniform Mo film is prepared as a back electrode layer by a magnetron sputtering process on a base substrate; and then the co-evaporation method or A uniform CIS-based absorption layer is prepared by processes such as sputtering selenization; a buffer layer is prepared by a chemical water bath method or a sputtering method on the CIS-based absorption layer, and an n-type layer and a TCO are prepared by magnetron sputtering. In the window layer, a gate line electrode is finally prepared.

The CIS-based thin-film solar cell prepared by this method has a small amount of light absorption and a large amount of carrier recombination, which are the main sources affecting the efficiency loss of the CIS-based thin-film solar cell. If the thickness of the CIS-based absorption layer is increased to increase the light absorption, The result is not only increased manufacturing costs, but also increased carrier recombination, which is contrary to reducing carrier recombination; if the carrier recombination is reduced by reducing the thickness of the CIS-based absorption layer, it will also reduce the amount of light absorption, Therefore, the research and development of a solar cell that can both increase the light absorption and reduce the carrier recombination is a technical problem to be solved urgently at present.

Summary of the invention

The embodiments of the present disclosure provide a solar cell and a method for preparing the same, the main purpose of which is to improve the light absorption of the light absorption layer and reduce the carrier recombination in the light absorption layer, thereby improving the performance of the solar cell.

According to an aspect of the present disclosure, a solar cell is provided, including:

Base substrate; and

A back electrode layer, a light absorption layer, a buffer layer, and a window layer, which are stacked and arranged on the base substrate and in a direction away from the base substrate;

Wherein, the surface of the back electrode layer in contact with the light absorption layer is a three-dimensional structure.

The solar cell provided by the embodiment of the present disclosure not only enhances the light reflection and light scattering of the interface between the back electrode layer and the light absorption layer through the three-dimensional structure contact surface provided between the back electrode layer and the light absorption layer, but also increases the light of the light absorption layer. Absorption, thereby increasing the photoelectric efficiency without increasing the thickness of the light absorbing layer, and enabling photo-generated carriers to be efficiently collected by the back electrode layer on the three-dimensional structure contact surface, reducing photo-generated carriers in the light-absorbing layer Recombination improves the collection efficiency of photo-generated carriers and improves the performance of solar cells.

Optionally, a surface of the back electrode layer in contact with the light absorbing layer has a convex portion and / or a concave portion, and the convex portion and / or the concave portion form a three-dimensional structure.

In one embodiment, the height of the protruding portion is in a range of 10 nm to 500 nm.

Optionally, the depth of the depression is in a range of 10 nm to 500 nm.

Optionally, the protruding portion includes a plurality of strip structures and / or a plurality of dot structures.

Optionally, the recessed portion includes a plurality of strip structures and / or a plurality of dot structures.

In one embodiment, a distance between two adjacent strip structures is in a range of 10 nm to 1000 nm.

Optionally, a plurality of the point-like structures are divided into a plurality of point-like structure groups, and each of the point-like structure groups consists of point-like structures located on the same straight line, and two adjacent point-like structure groups The pitch is in the range of 10nm to 1000nm.

According to another aspect of the present disclosure, a method for preparing a solar cell is provided, and the method includes:

Depositing the back electrode layer on the base substrate;

Preparing the three-dimensional structure on a surface of the back electrode layer facing away from the base substrate;

Preparing the light absorption layer on the back electrode layer having a three-dimensional structure;

A buffer layer and a window layer are prepared on the light absorbing layer.

The method for preparing a solar cell provided in the embodiment of the present disclosure, the preparation method prepares a three-dimensional structure on the surface of the back electrode layer after the back electrode layer is deposited, so that the interface between the light absorption layer and the back electrode layer is a three-dimensional structure interface. Through the formation of the three-dimensional structure interface, the light absorption amount of the light absorption layer is enhanced and the photogenerated carrier recombination in the light absorption layer is reduced.

BRIEF DESCRIPTION OF THE DRAWINGS

1 is a schematic structural diagram of a solar cell according to an embodiment of the present disclosure;

2 is a schematic structural diagram of a three-dimensional structure contact surface according to an embodiment of the present disclosure;

3 is a schematic structural diagram of another three-dimensional structure contact surface according to an embodiment of the present disclosure;

4 is a schematic structural diagram of another three-dimensional structure contact surface according to an embodiment of the present disclosure;

5 is a schematic structural diagram of another three-dimensional structure contact surface according to an embodiment of the present disclosure;

FIG. 6 is a flowchart of a method for manufacturing a solar cell according to an embodiment of the present disclosure.

detailed description

The solar cell and the manufacturing method thereof according to the embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings.

In the description of the present disclosure, the terms “first” and “second” are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as “first” and “second” may explicitly or implicitly include one or more of the features. In the description of the present disclosure, unless otherwise stated, "a plurality" means two or more.

In the description of this disclosure, it should be noted that the terms "installation", "connected", and "connected" should be understood in a broad sense unless explicitly stated and limited otherwise. For example, they can be fixed or removable. Connected or integrated; it can be mechanical or electrical; it can be directly connected or it can be indirectly connected through an intermediate medium, or it can be the communication between the two segments. For those of ordinary skill in the art, the meanings of the above terms in the present disclosure can be understood according to specific situations.

The term "and / or" in this document is only a kind of association relationship describing related objects, which means that there can be three kinds of relationships, for example, A and / or B can mean: A exists alone, A and B exist simultaneously, and exists alone B these three cases. In addition, the character "/" in this article generally indicates that the related objects are an "or" relationship.

An embodiment of the present disclosure provides a solar cell. Referring to FIG. 1 to FIG. 5, the solar cell includes: a base substrate 1, which is disposed on the base substrate 1 and is stacked in a direction away from the base substrate 1. The back electrode layer 2, the light absorption layer 3, the buffer layer 4 and the window layer 5, wherein a surface of the back electrode layer 2 and the light absorption layer 3 in contact is a three-dimensional structure 201.

Since the surface of the back electrode layer 2 in contact with the light absorption layer 3 is a three-dimensional structure 201, when the light absorption layer 3 is deposited on the three-dimensional structure 201, a light trapping structure can be formed. The light trapping structure can enhance the back surface. The light reflection, scattering, and refraction at the interface between the electrode layer 2 and the light absorption layer 3 can effectively increase the light absorption compared to the two-dimensional structure contact surface, and effectively increase the light absorption without increasing the thickness of the light absorption layer. The effect of improving the photoelectric efficiency of the solar cell. In addition, compared with increasing the thickness of the light absorbing layer 3, the method of the present disclosure for setting the three-dimensional structure 201 also reduces the manufacturing cost. At the same time, due to the existence of the three-dimensional structure, when the photo-generated carriers generated in the light-absorbing layer 3 are collected by the back electrode layer 2, the path of the photo-generated carriers can be shortened, and the photo-generated carriers can be reduced to recombine in the light-absorbing layer 3. Probability, thereby increasing the collection efficiency of photo-generated carriers by the back electrode layer 2 and improving the performance of the solar cell.

For example, a surface of the back electrode layer 2 in contact with the light absorption layer 3 has a convex portion and / or a concave portion, and the convex portion and / or the concave portion form a three-dimensional structure 201. The three-dimensional structure may be formed by a convex portion, a concave portion, or a combination of a convex portion and a concave portion.

When the three-dimensional structure includes the protruding portion, the height of the protruding portion is in a range of 10 nm to 500 nm. When the three-dimensional structure includes the recessed portion, the depth of the recessed portion is between In the range of 10nm to 500nm. The use of convex portions with a height in the range of 10nm to 500nm and depressions with a depth in the range of 10nm to 500nm can optimize the light absorption and collection efficiency of photo-generated carriers; if the size is too large, light absorption will be reduced The thickness of the layer, compared with the increased light absorption of the three-dimensional structure, decreases the light absorption of the reduced absorption layer thickness, which affects the photoelectric efficiency of the entire solar cell; if the size is small, it cannot effectively increase The effect of the amount of light absorption and the effect of improving the collection efficiency of photo-generated carriers. In one embodiment, a height of the protruding portion is in a range of 100 nm to 300 nm, and a depth of the recessed portion is in a range of 100 nm to 300 nm.

The protruding portion may have various structures. For example, the protruding portion may include a plurality of strip-shaped structures and / or a plurality of dot-shaped structures, and the protruding portion may include a plurality of strip-shaped structures. The structural composition (refer to FIG. 2) may be composed of a plurality of dot-like structures (refer to FIG. 3), or may be composed of a plurality of strip-like structures and a plurality of dot-like structures arranged at intervals or other layout methods.

For example, the cross-sectional shape of the strip structure may have various shapes, for example: rectangular, trapezoidal, triangular, semi-circular, fan-shaped, or arc-shaped. The strip structure may be one of the above-mentioned various shapes. A plurality of combinations may be used, which is not limited here.

For example, the point structure may have multiple types, such as a cylinder, a trapezoidal cube, a conical cube, or a hemisphere. Similarly, the point structure may be one of the above shapes, or a combination of multiple types may be used. It is not limited here.

In implementation, when a plurality of the strip-like structures form a three-dimensional structure, or a plurality of dot-like structures form a three-dimensional structure, in order to achieve better light trapping and reduce the effect of photogenerated carrier recombination, two adjacent ones The spacing between the strip structures can be in the range of 10 nm to 1000 nm. Optionally, a distance between two adjacent strip structures may be in a range of 100 nm to 800 nm. Optionally, the spacing between each two adjacent strip-shaped structures is equal, and a plurality of the point-shaped structures are divided into a plurality of point-shaped structure groups, and each of the point-shaped structure groups is composed of It is composed of a dot structure, and the distance between two adjacent dot structure groups is in a range of 10 nm to 1000 nm. Optionally, the distance between two adjacent dot structure groups is in a range of 100 nm to 800 nm, and the distance between two adjacent dot structures in each of the dot structure groups is also in a range of 10 nm to 1000 nm. Inside. Optionally, the distance between two adjacent dot-like structures is also in the range of 100 nm to 800 nm, and the distance between two adjacent dot-like structures can be similar to that of two adjacent dot-like structures. The spacing between the dot structures may be equal or unequal. Optionally, at least part of the dot-like structure groups have equal pitches between each two adjacent dot-like structures or each of the dot-like structure groups have equal pitches between each two adjacent dot-like structures, Such a design is also convenient for preparing the above-mentioned strip structure or dot structure, so that the strip structure or dot structure has a periodic layout, but the strip structure or dot structure may also be laid irregularly.

The recessed portion may also have various structures. For example, the recessed portion may include a plurality of strip structures and / or a plurality of dot structures, wherein the recessed portions may include a plurality of strip structures. The composition (refer to FIG. 4) may be composed of a plurality of dot-like structures (refer to FIG. 5), or may be composed of a plurality of strip-like structures and a plurality of dot-like structures arranged at intervals or other layout methods.

By way of example, the cross-sectional shape of the strip structure may be various, for example: rectangular, trapezoidal, triangular, semi-circular, fan-shaped, or arc-shaped. The strip structure may be one of the above-mentioned various shapes, or may be It is a combination of a plurality of types, and is not specifically limited.

For example, the point structure also has multiple types, such as a cylinder, a trapezoidal cube, a conical cube, or a hemisphere. Similarly, the point structure may be one of the above shapes, or a combination of multiple types. It is not limited here.

During implementation, when a plurality of the strip structures form a three-dimensional structure, or when a plurality of dot structures form a three-dimensional structure, a distance between two adjacent strip structures is 10 nm to 1000 nm, and optionally, adjacent The distance between the two strip structures can be in the range of 100 nm to 800 nm. Optionally, the spacing between each two adjacent strip-shaped structures is equal, and a plurality of the point-shaped structures are divided into a plurality of point-shaped structure groups, and each of the point-shaped structure groups is composed of It is composed of a dot structure, and the distance between two adjacent dot structure groups is in a range of 10 nm to 1000 nm. Optionally, the distance between two adjacent dot-like structure groups is in a range of 100 nm to 800 nm, and the distance between two adjacent dot-like structures in each of the dot-like structure groups is within a range of 10 nm-1000 nm. . Optionally, the distance between two adjacent dot-like structures is in a range of 100 nm to 800 nm, and the distance between the two adjacent dot-like structures may be the same as that of two adjacent dots in each of the dot-like structures. The spacing between the structures may be equal or unequal. Optionally, at least part of the dot-like structure groups have equal pitches between each two adjacent dot-like structures or each of the dot-like structure groups have equal pitches between each two adjacent dot-like structures, Such a design is also convenient for preparing the above-mentioned strip structure or dot structure, so that the strip structure or dot structure has a periodic layout, but the strip structure or dot structure may also be laid irregularly.

The composition of the three-dimensional structure and the composition of the back electrode layer may be the same, for example, molybdenum or other metal materials are used.

Exemplarily, the solar cell may be a CIS-based thin-film solar cell, a cadmium telluride cell, a gallium arsenide cell, or an amorphous silicon thin-film solar cell.

An embodiment of the present disclosure also provides a preparation method for preparing the solar cell. Referring to FIG. 6, the preparation method includes:

S1: Provide a base substrate. Wherein, the base substrate is a stainless steel substrate.

S2: depositing the back electrode layer on the base substrate.

Deposition by one of physical vapor deposition (PVD) or chemical vapor deposition (CVD). Magnetron sputtering, low pressure chemical vapor deposition (LPCVD), atmospheric pressure chemical vapor deposition (APCVD), or reactive plasma can be used for deposition. Bulk deposition (RPD) is used for deposition. Among them, magnetron sputtering is a more commonly used deposition method.

The back electrode layer is a Mo back electrode layer, and other metals may also be used as the material of the back electrode layer.

S3: preparing the three-dimensional structure on a surface of the back electrode layer facing away from the base substrate, wherein a component of the three-dimensional structure and a component of the back electrode layer may be the same.

When preparing the three-dimensional structure, a variety of methods can be used to prepare the three-dimensional structure.

One method is to print the three-dimensional structure on the back electrode layer by using an optical lithography process, and the optical lithography process may be electronic lithography, atomic lithography, extreme ultraviolet lithography, or X-ray lithography.

Another method is to emboss the three-dimensional structure on the back electrode layer by using a nano-imprint process or a soft engraving process.

A third exemplary method is to use a scanning probe process to imprint the three-dimensional structure on the back electrode layer.

In one embodiment of the present disclosure, the preparation of the three-dimensional structure is achieved by using atomic lithography and nano-imprinting processes.

S4: The light absorption layer is prepared on the back electrode layer having a three-dimensional structure, and the light absorption layer is embedded on the back electrode layer having the three-dimensional structure to form a light trapping structure.

The light absorption layer can be prepared by a co-evaporation method or a sputtering method. Generally, the light absorption layer is a CIS-based light absorption layer. After the light absorption layer is prepared, the light absorption layer forms a light trapping structure on a three-dimensional structure. The technical effects achieved by the light trapping structure have been described in detail above, and are not repeated here.

S5: A buffer layer and a window layer are sequentially prepared on the light absorbing layer to obtain a solar cell.

Exemplarily, a buffer layer is prepared on a light absorbing layer by a chemical bath deposition method for the first time. Generally, the buffer layer is a cadmium sulfide buffer layer, and then a window layer is prepared on the buffer layer by magnetron sputtering. The material of the window layer may be one of indium oxide, indium tin oxide, titanium-doped indium oxide, tungsten oxide, boron-doped zinc oxide, or aluminum-doped zinc oxide.

The features, structures, materials, or characteristics described in this specification may be combined in any suitable manner in any one or more embodiments or examples.

The foregoing is merely an exemplary embodiment of the present disclosure, but the scope of protection of the present disclosure is not limited to this. Any person skilled in the art can easily think of changes or replacements within the technical scope disclosed in the present disclosure. All should be covered by the protection scope of this disclosure. Therefore, the protection scope of the present disclosure shall be subject to the protection scope of the claims.

Claims

A solar cell includes:

Base substrate; and

A back electrode layer, a light absorption layer, a buffer layer, and a window layer, which are stacked and arranged on the base substrate and in a direction away from the base substrate;

Wherein, a surface of the back electrode layer that is in contact with the light absorption layer is a three-dimensional structure.
The solar cell according to claim 1, wherein a surface of the back electrode layer in contact with the light absorption layer has a protrusion and / or a depression, and the protrusion and / or the depression form a three-dimensional shape. structure.
The solar cell according to claim 2, wherein a height of the protruding portion is in a range of 10 nm to 500 nm.
The solar cell according to claim 2, wherein a depth of the recessed portion is in a range of 10 nm to 500 nm.
The solar cell according to claim 2, wherein the protruding portion includes a plurality of strip structures and / or a plurality of dot structures.
The solar cell according to claim 2, wherein the recessed portion includes a plurality of strip-like structures and / or a plurality of dot-like structures.
The solar cell according to claim 5 or 6, wherein a pitch between two adjacent strip structures is in a range of 10 nm to 1000 nm.
The solar cell according to claim 5 or 6, wherein a plurality of the dot-like structures are divided into a plurality of dot-like structure groups, each of the dot-like structure groups is composed of dot-like structures located on a same straight line, and The distance between two adjacent dot-shaped structures is in a range of 10 nm to 1000 nm.
The solar cell according to claim 1, wherein the buffer layer and the window layer are sequentially formed on the light absorption layer.
A method for preparing a solar cell includes:

Depositing a back electrode layer on a base substrate;

Preparing a three-dimensional structure on a surface of the back electrode layer facing away from the base substrate;

Preparing a light absorption layer on the back electrode layer having a three-dimensional structure;

A buffer layer and a window layer are sequentially prepared on the light absorbing layer.
The manufacturing method according to claim 10, wherein the step of preparing the three-dimensional structure on a surface of the back electrode layer facing away from the base substrate substrate comprises: using an optical lithography process on the back electrode layer The three-dimensional structure is engraved.
The manufacturing method according to claim 11, wherein the optical lithography process comprises one of electronic lithography, atomic lithography, extreme ultraviolet lithography, or X-ray lithography.
The manufacturing method according to claim 10, wherein the step of preparing the three-dimensional structure on a surface of the back electrode layer facing away from the base substrate comprises: applying a nano-imprint process or a soft engraving technique on the surface. The three-dimensional structure is imprinted on the back electrode layer.
The method according to claim 10, wherein the step of preparing the three-dimensional structure on a surface of the back electrode layer facing away from the base substrate substrate comprises: using a scanning probe process on the back electrode layer The three-dimensional structure is embossed.