CN110047966B

CN110047966B - CIGS solar cell with flexible substrate and preparation method thereof

Info

Publication number: CN110047966B
Application number: CN201910347128.8A
Authority: CN
Inventors: 张准; 王磊
Original assignee: Chaozhou Yijia Photoelectric Technology Co ltd
Current assignee: Sunflare Nanjing Energy Technology Co ltd
Priority date: 2019-04-26
Filing date: 2019-04-26
Publication date: 2020-06-16
Anticipated expiration: 2039-04-26
Also published as: CN110047966A

Abstract

The invention relates to a CIGS (copper indium gallium selenide) solar cell with a flexible substrate and a preparation method thereof, belongs to the technical field of CIGS solar cells, and solves the technical problems that the existing CIGS solar thin-film cell is low in light absorption rate and difficult to apply to curved-surface-shaped photovoltaic buildings and mobile photovoltaic power stations. The flexible substrate CIGS solar cell comprises a substrate, and a back electrode layer, a reflecting layer, an absorbing layer, a first buffer layer and a transparent surface electrode layer which are sequentially stacked on the substrate; an alkali metal doped composite layer is arranged between the reflecting layer and the absorbing layer, at least one channel is correspondingly arranged on the alkali metal doped composite layer and the reflecting layer, a back electrode layer is arranged at the bottom of the channel, a Mo electrode thin film layer is arranged on the side wall of the channel, and a part of the absorbing layer is filled in the channel and is in direct physical contact with the back electrode layer. The flexible substrate CIGS solar cell provided by the invention has high light absorptivity, and can be used for curved surface modeling of photovoltaic buildings and mobile photovoltaic power stations in a large scale.

Description

CIGS solar cell with flexible substrate and preparation method thereof

Technical Field

The invention relates to the technical field of CIGS solar cells, in particular to a CIGS solar cell with a flexible substrate and a preparation method thereof.

Background

Under the condition of scientific and technical level at the present stage, people widely use traditional energy sources such as coal, petroleum, natural gas and the like; however, most of these conventional energy sources are non-renewable energy sources and cause air pollution when being used. To avoid air pollution caused by traditional energy sources, more and more countries are beginning to vigorously develop new energy sources. Solar energy is an inexhaustible new energy, and solar energy utilization technology is vigorously developed in various countries. The solar photovoltaic power generation has the advantages of zero emission, safety, reliability, no noise, no pollution, inexhaustible resources, short construction period, long service life and the like, so that the solar photovoltaic power generation is concerned.

The solar cell is a device for directly converting light energy into electric energy through a photoelectric effect or a photochemical effect, and the flexible substrate CIGS solar cell refers to a solar cell with a substrate made of materials such as metal foil or high molecular polymer. Due to their lightweight flexibility, foldability, and resistance to impact, flexible-substrate CIGS solar cells are used primarily for curved molding of photovoltaic buildings and for mobile photovoltaic charging devices.

The Copper Indium Gallium Selenide (CIGS) solar cell mainly comprises Cu (copper), In (indium), Ga (gallium) and Se (selenium), and has the advantages of strong light absorption capacity, good power generation stability, high conversion efficiency, long power generation time In the daytime, high power generation amount, low production cost, short energy recovery period and the like.

A CIGS solar cell generally includes a substrate, a back electrode layer, a CIGS layer (light absorbing layer), a buffer layer, and a surface electrode layer, wherein the CIGS layer is composed of Cu (In, Ga) Se₂To reduce the defect density of the CIGS layer and increase the carrier concentration, the existing solar thin film materials are usually compounds doped with alkali metals, such as NaF and Na, in the CIGS layer or the back electrode layer adjacent to the CIGS layer₂Se、Na₂S、Na₂SeO₃Or NaNbO₃Etc., but new impurity elements, such as F, S, etc., are introduced during the doping process.

In addition, in the aerospace field, CIGS solar cells are required to have higher mass-specific power, i.e., more electricity per mass of solar cells is desired to be generated. The CIGS solar thin film cell in the prior art has low light absorption rate and is difficult to be applied to the photovoltaic buildings with curved surface modeling. Therefore, a new film material is needed to improve the light energy utilization efficiency of the CIGS solar cell, thereby improving the cell performance.

Disclosure of Invention

In view of the foregoing analysis, embodiments of the present invention are directed to a CIGS solar cell with a flexible substrate and a method for manufacturing the same, so as to solve the technical problems that the conventional CIGS solar thin film cell has low light absorption rate and is difficult to be applied to curved photovoltaic buildings and mobile photovoltaic power stations.

The invention discloses a flexible substrate CIGS solar cell, which comprises a substrate, and a back electrode layer, a reflecting layer, an absorbing layer, a first buffer layer, a high-impedance layer and a transparent surface electrode layer which are sequentially stacked on the flexible substrate; an alkali metal doped composite layer is arranged between the reflecting layer and the absorbing layer, at least one channel is correspondingly arranged on the alkali metal doped composite layer and the reflecting layer, a back electrode layer is arranged at the bottom of the channel, a Mo electrode thin film layer is arranged on the side wall of the channel, and a part of the absorbing layer is filled in the channel and is in direct physical contact with the back electrode layer.

In one possible design, the absorber layer is divided into a first CIGS absorber layer, a second CIGS absorber layer, and a third CIGS absorber layer with successively increasing band gap widths, with a portion of the third CIGS absorber layer filling the channel and in physical contact with the back electrode layer.

In a possible design, the back electrode layer is a Mo back electrode composite structure, the Mo back electrode composite structure sequentially includes a first sub Mo electrode layer, a first stress buffer layer, a second sub Mo electrode layer, a second stress buffer layer, and a third sub Mo electrode layer from top to bottom, and thicknesses of the first sub Mo electrode layer, the second sub Mo electrode layer, and the third sub Mo electrode layer are sequentially reduced.

In one possible design, the first stress buffer layer and the second stress buffer layer are both Ag films, and the thickness of the first stress buffer layer is larger than that of the second stress buffer layer; the substrate is made of polyimide, and the polyimide is in contact with the third Mo electrode layer.

In one possible design, the high-resistance layer is an intrinsic zinc oxide high-resistance layer, the transparent surface electrode layer comprises an ITO low-resistance layer, and an Al electrode is arranged on the ITO low-resistance layer.

In one possible design, the transparent surface electrode layer is an ITO-Ag-ITO transparent thin film layer, and an Al electrode is arranged on the ITO-Ag-ITO transparent thin film layer.

In one possible design, the buffer layer is an InS and InSe composite buffer layer; the InS and InSe composite buffer layers are alternately arranged.

In one possible design, the transparent surface electrode layerAn anti-reflection layer is arranged above the substrate and is MgF₂And a film, the antireflection layer for reducing reflection of light in the ITO low resistance layer.

In one possible design, a barrier layer is arranged between the polyimide film and the back electrode layer, the barrier layer at least comprises three layers, and the three layers of the barrier layer are respectively a silver layer, a copper layer or a titanium layer; the barrier layer is used for blocking impurity elements in the substrate from entering the absorption layer.

In one possible design, the barrier layer includes a first sub-barrier layer, a second sub-barrier layer, and a third sub-barrier layer, the first sub-barrier layer is in contact with the back electrode layer, and the third sub-barrier layer is in contact with the polyimide film substrate.

In one possible design, the alkali metal-doped composite layer is a Na-doped composite layer structure; the Na-doped composite layer structure comprises a first Na doped layer, a second Na doped layer and a third Na doped layer, and the Na doping amount of the first Na doped layer is larger than the second Na doping amount and larger than the third Na doping amount.

The invention also discloses a preparation method of the flexible substrate CIGS solar cell, which comprises the following steps:

s1, preparing a back electrode layer on the solar cell substrate;

s2, preparing a reflecting layer and an alkali metal doped composite layer on the back electrode layer;

s3, depositing a third CIGS absorption layer on the back electrode layer by adopting a multi-step sputtering method, and depositing a second CIGS absorption layer and a first CIGS absorption layer on the third CIGS absorption layer;

s4, preparing a buffer layer on the third CIGS absorption layer; preparing an intrinsic zinc oxide high-impedance layer on the buffer layer; preparing an indium tin oxide thin film low-impedance layer on the intrinsic zinc oxide high-impedance layer;

s5, preparing an aluminum electrode on the low-impedance layer of the indium tin oxide film, and preparing an anti-reflection layer on the Al electrode.

The invention also discloses a packaging structure for packaging the flexible substrate CIGS solar cell, which is rectangular and comprises a protective film, a structural film and a back film which are compacted from top to bottom; the size of the structured film and the flexible substrate CIGS solar cell are the same; the size of the back film is larger than that of the flexible substrate CIGS solar cell; the protective film comprises a main body and side portions, the main body is the same as the flexible substrate CIGS solar cell in size, the side portions are arranged on four sides of the main body and are integrated with the main body into a whole, and the side portions are sealed and tightly cover the side faces of the structural film and the flexible substrate CIGS solar cell and are tightly pressed with the back film.

Compared with the prior art, the invention can realize at least one of the following beneficial effects:

(1) the absorption layer adopts the first to third CIGS absorption layers, the band gap widths of the first CIGS absorption layer, the second CIGS absorption layer and the third CIGS absorption layer are sequentially increased, the first CIGS absorption layer is partially filled in the channel and is in physical contact with the back electrode layer, after sunlight sequentially passes through the third CIGS absorption layer, the second CIGS absorption layer and the first CIGS absorption layer, part of unabsorbed light rays after the sunlight passes through the three semiconductor absorption layers are reflected by the reflection layer and then return to the three semiconductor absorption layers, and the reflection layer performs an absorption process again, so that the reflection layer plays a role in light trapping. Therefore, the flexible substrate CIGS solar cell can absorb incident light more effectively, improves conversion efficiency and output power, and has better sunlight absorption performance under the conditions of low incident light and scattered light.

(2) According to the invention, a Mo back electrode composite structure is adopted, a first sub Mo electrode layer of the Mo back electrode composite structure is contacted with a reflecting layer and a third CIGS absorbing layer, a first stress buffer layer, a second sub Mo electrode layer, a second stress buffer layer and a third sub Mo electrode layer are sequentially arranged below the first sub Mo electrode layer, and a polyimide film layer is arranged below the third sub Mo electrode layer; on the other hand, the Mo back electrode composite structure can effectively reduce the problem of overlarge stress caused by the mismatching of the thermal expansion coefficients between the polyimide film and the back electrode layer; on the other hand, the Mo back electrode composite structure can greatly improve the reflectivity of the back electrode layer in red light and near infrared regions, and improve the efficiency of the CIGS solar cell.

(3) The second conducting layer adopts a high-transparency composite conducting layer ITO-Ag-ITO film, and compared with a single-layer ITO film, the high-transparency composite conducting layer ITO-Ag-ITO film has high visible light transmittance and conductivity in an Ag film layer, so that the high-transparency composite conducting layer ITO-Ag-ITO film has high conductivity and smaller sheet resistance; in addition, because the thickness of the ITO film is approximately the same as that of the single-layer ITO film, In the ITO film is greatly saved, and the cost of the ITO is finally reduced.

In the invention, the technical schemes can be combined with each other to realize more preferable combination schemes. Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.

Drawings

The drawings are only for purposes of illustrating particular embodiments and are not to be construed as limiting the invention, wherein like reference numerals are used to designate like parts throughout.

Fig. 1 is a schematic diagram of the overall structure of a flexible substrate CIGS solar cell of the present invention;

fig. 2 is a schematic diagram of the structure of the absorber layer of the flexible substrate CIGS solar cell of the present invention;

fig. 3 is a schematic diagram of the structure of the back electrode layer of the flexible substrate CIGS solar cell of the present invention;

fig. 4 is a schematic diagram of the structure of the transparent surface electrode layer of the flexible substrate CIGS solar cell of the present invention;

fig. 5 is a schematic view of the structure of the first surface electrode layer of the flexible substrate CIGS solar cell of the present invention;

fig. 6 is a schematic diagram of the structure of the second surface electrode layer of a flexible substrate CIGS solar cell of the present invention;

fig. 7 is a schematic view of the position of the first surface electrode layer and the shape memory alloy fiber layer of the flexible substrate CIGS solar cell of the present invention;

fig. 8 is a cross-sectional view of the transparent surface electrode layer of a flexible substrate CIGS solar cell of the present invention;

fig. 9 is a schematic diagram of an encapsulation structure of a flexible substrate CIGS solar thin film cell provided in example 3 of the present invention;

fig. 10 is a cross-sectional view of an encapsulation structure of a flexible base CIGS solar thin film cell provided in example 4 of the present invention;

fig. 11 is a schematic structural diagram of a package tool provided in embodiment 5 of the present invention.

Reference numerals:

1-a flexible substrate; 2-a back electrode layer; 21-a first sub-Mo electrode layer; 22-a first stress buffer layer; 23-a second sub-Mo electrode layer; 24-a second stress buffer layer; 25 a third sub-Mo electrode layer; 3-a reflective layer; 4-an alkali metal doped composite layer; 5-Mo electrode thin film layer; 6-an absorbing layer; 61-a first CIGS absorber layer; 62-a second CIGS absorber layer; 63-a third CIGS absorber layer; 7-a buffer layer; 8-intrinsic zinc oxide high-resistance layer; 9-a transparent surface electrode layer; 91-a first surface electrode layer; 911-first ITO region; 912-first IZTO zone; 92-a second surface electrode layer; 921 — second ITO region; 922-a second IZTO zone; 93-shape memory alloy fibers; a 10-Al electrode; 11-an anti-reflection layer; 12-a package structure; a 121-ETFE membrane; 122-POE glue; 123-EEA film; 124-EVA glue; 125-CIGS cell power source; 126-PVB glue; a 127-DNP film; 128-PET film.

Detailed Description

The accompanying drawings, which are incorporated in and constitute a part of this application, illustrate preferred embodiments of the invention and together with the description, serve to explain the principles of the invention and not to limit the scope of the invention.

Example 1

The invention provides a flexible substrate CIGS solar cell, which comprises a substrate, a back electrode layer 2, a reflecting layer 3, an absorbing layer 6, a buffer layer 7 and a transparent surface electrode layer 9, wherein the back electrode layer 2, the reflecting layer 3, the absorbing layer 6, the buffer layer 7 and the transparent surface electrode layer 9 are sequentially stacked on the substrate as shown in figure 1; an alkali metal doped composite layer 4 is arranged between the reflecting layer 3 and the absorbing layer 6, at least one channel is correspondingly arranged on the alkali metal doped composite layer 4 and the reflecting layer 3, the bottom of the channel is a back electrode layer 2, the side wall of the channel is an Mo substrate electrode thin film layer, and the absorbing layer 6 is partially filled in the channel and is in direct physical contact with the back electrode layer 2.

Specifically, the substrate of the flexible substrate CIGS solar cell is a flexible substrate 1, a back electrode layer 2, a reflecting layer 3, an absorbing layer 6 and a buffer layer 7 are arranged above the flexible substrate 1, a transparent surface electrode layer 9 is arranged above the buffer layer 7, an alkali metal doped composite layer 4 is arranged between the reflecting layer 3 and the absorbing layer 6, alkali metal ions released by the alkali metal doped composite layer 4 can greatly promote the absorption of the absorbing layer 6 to sunlight, at least one channel is correspondingly arranged on the alkali metal doped composite layer 4 and the reflecting layer 3, a Mo electrode thin film layer 5 is arranged on the side wall of the channel, the bottom of the channel is the back electrode layer 2, a part protrudes from the lower part of the absorbing layer 6, the protruding part is filled in the channel, the side wall of the protruding part is in direct physical contact with the Mo electrode thin layer 5, and the bottom of the protruding part is in direct physical contact with the back electrode layer 2, the convex part of the absorbing layer 6 is filled in the channel, so that the absorbing layer 6 can be in good physical contact with the Mo electrode thin film layer 5 and the back electrode layer 2, and further the light energy absorbed by the absorbing layer 6 is converted into electric energy to be transmitted, and the light energy conversion efficiency is improved.

In addition, compared with the prior art, the flexible substrate 1 is adopted in the flexible substrate CIGS solar cell provided by the embodiment, and the flexible substrate 1 enables the CIGS solar cell to have flexibility, foldability and falling-collision resistance, so that the CIGS solar cell can better match the curved surface modeling of a ground photovoltaic building and the requirements of a mobile photovoltaic power station, is easy to implement, is favorable for large-scale popularization and application of the CIGS solar cell, and finally promotes the development of the CIGS solar cell.

In order to sufficiently absorb the incident solar light, as shown in fig. 2, the absorption layer 6 is divided into a first CIGS absorption layer 61, a second CIGS absorption layer 62 and a third CIGS absorption layer 63, wherein the band gap widths of the first CIGS absorption layer 61, the second CIGS absorption layer 62 and the third CIGS absorption layer 63 are sequentially increased, and the lower end protruding portion of the third CIGS absorption layer 63 is filled in the channel and is in direct physical contact with the back electrode layer 2.

Specifically, after sunlight passes through the conductive layer, the intrinsic zinc oxide high-resistance layer 8 and the buffer layer 7, enters the interface between the absorption layer 6 and the buffer layer 7, and then sequentially passes through the third CIGS absorption layer 63, the second CIGS absorption layer 62 and the first CIGS absorption layer 61, after the sunlight passes through the three semiconductor absorption layers 6, a part of unabsorbed light is reflected by the reflection layer 3, and then returns to the three semiconductor absorption layers 6, and then the absorption process is performed once again, so that the reflection layer 3 plays a role in light trapping. Therefore, the flexible CIGS solar cell can absorb incident light more effectively, improves conversion efficiency and output power, and has better sunlight absorption performance under the conditions of low incident light and scattered light.

In the present invention, the bottom of the third CIGS absorber 63 is filled in the channel between the alkali metal-doped composite layer 4 and the reflector 3, and the structural design of the third CIGS absorber 63 can reduce the occupied volume of the absorber 6, thereby ensuring that the solar cell can be sufficiently absorbed while the volume of the absorber 6 is ensured.

In order to prepare a flexible substrate CIGS solar cell, the flexible substrate 1 of the present invention employs a polyimide film, and meanwhile, in order to balance the problem of mismatch of thermal expansion coefficients between the polyimide film and the back electrode layer 2, as shown in fig. 3, the back electrode layer 2 of the present invention is an Mo back electrode composite structure, the Mo back electrode composite structure sequentially includes, from top to bottom, a first sub-Mo electrode layer 21, a first stress buffer layer 22, a second sub-Mo electrode layer 23, a second stress buffer layer 24, and a third sub-Mo electrode layer 25, and thicknesses of the first sub-Mo electrode layer 21, the second sub-Mo electrode layer 23, and the third sub-Mo electrode layer 25 are sequentially reduced.

Specifically, as Mo has good conductivity, chemical stability and physical property and can form ohmic contact with a CIGS thin film, the invention adopts a Mo back electrode composite structure, a first sub Mo electrode layer 21 of the Mo back electrode composite structure is contacted with the reflecting layer 3 and a third CIGS absorbing layer 63, a first stress buffer layer 22, a second sub Mo electrode layer 23, a second stress buffer layer 24 and a third sub Mo electrode layer 25 are sequentially arranged below the first sub Mo electrode layer 21, a polyimide thin film layer is arranged below the third sub Mo electrode layer 25, and the back electrode layer 2 is designed into the Mo back electrode composite structure, so that the resistivity of the CIGS solar cell can be greatly reduced, the light reflection rate is higher, and the improvement on the efficiency of the flexible substrate CIGS solar cell is important; on the other hand, the Mo back electrode composite structure can effectively reduce the problem of overlarge stress caused by the mismatching of the thermal expansion coefficients between the polyimide film and the back electrode layer 2; on the other hand, the Mo back electrode composite structure can greatly improve the reflectivity of the back electrode layer 2 in red light and near infrared regions, and improve the efficiency of the CIGS solar cell.

In order to further ensure the problem of thermal expansion coefficient mismatch between the flexible layer and the back electrode layer 2, in the invention, the first stress buffer layer 22 and the second stress buffer layer 24 are both Ag thin film layers, and the thickness of the first stress buffer layer 23 is greater than that of the second stress buffer layer 24. Because the resistivity of the Ag film is relatively low and the Ag film has good conductivity, the first stress buffer layer 22 and the second stress buffer layer 24 disposed in the back electrode layer 2 can balance the thermal expansion coefficient between the polyimide film and the back electrode layer 2 to the greatest extent, and in addition, the first buffer layer, the second buffer layer, and the third buffer layer can effectively prevent Ag from diffusing to the third CIGS absorption layer 63, thereby preventing the diffusion of Ag from affecting the performance of the CIGS thin film battery.

It should be noted that, considering that the polyimide film has a large thermal expansion coefficient, the polyimide is likely to deform at high temperature, but in order to manufacture a flexible CIGS solar cell, the present invention may also adopt a flexible-rigid composite substrate, where the flexible-rigid composite substrate is a composite substrate of polyimide and glass, the polyimide layer is deposited on the glass, and the thickness of the polyimide film is 25-30 μm.

In order to increase the penetration of sunlight, the high-impedance layer is an intrinsic zinc oxide high-impedance layer 8, the transparent surface electrode layer 9 comprises an ITO low-impedance layer, and an Al electrode 10 is arranged on the ITO low-impedance layer.

Because ITO is a wide-energy-band thin film material, the ITO has high conductivity, high visible light transmittance, extremely low sheet resistance and an ultra-flat transparent conductive film, the transparent surface electrode layer 9 is selected as an ITO low-impedance layer.

In addition, in order to reduce the sheet resistance of the second transparent layer, the transparent surface electrode layer 9 of the invention can also be a high-transparent composite conductive layer ITO-Ag-ITO film, the visible light transmittance and the conductivity in the Ag film layer are also high, and compared with a single-layer ITO film, the high-transparent composite conductive layer ITO-Ag-ITO film has strong conductivity and smaller sheet resistance; in addition, the thickness of the high-transparency composite conductive layer ITO-Ag-ITO film is 0.3-0.8 μm; the thickness of the film is approximately the same as that of a single-layer ITO film, In the ITO film is greatly saved, and the cost of the ITO is finally reduced.

In order to improve the water vapor barrier property of the CIGS layer, the transparent surface electrode layer 9 may be made of Indium Zinc Tin Oxide (IZTO). The IZTO is adopted to replace a common material ITO of the transparent surface electrode layer 9, the structural compactness of the IZTO is superior to that of the ITO, and the water vapor barrier property of the IZTO is higher than that of the ITO, so that the transparent surface electrode layer 9 made of the IZTO can better protect the buffer layer 7 sensitive to water vapor and the CIGS layer, and the working stability of the barrier CIGS solar cell is improved.

Considering that the light transmittance of IZTO is lower than that of ITO, in order to reduce the influence of IZTO on the light transmittance of the transparent surface electrode layer 9, the transparent surface electrode layer 9 of the present invention may also be designed to be a composite layer structure, as shown in fig. 4 to 8, the composite layer structure includes a first surface electrode layer 91 and a second surface electrode layer 92, one of which includes IZTO and the other includes ITO, that is, the transparent surface electrode layer 9 includes both IZTO and ITO, so that the transparent surface electrode layer can combine the good water vapor barrier property of IZTO and the good light transmittance of ITO, and can improve the water vapor barrier property on the basis of not influencing the light transmittance of the transparent surface electrode layer 9. The relative positions of the first surface electrode layer 91 and the second surface electrode layer 92 may be adjusted according to the actual situation, in which the first surface electrode layer 91 is close to the intrinsic zinc oxide high-resistance layer 8 or the second surface electrode layer 92 is close to the intrinsic zinc oxide high-resistance layer 8.

In consideration of the water vapor barrier property of the second transparent surface electrode layer 9, since the water vapor barrier property of ITO is lower than that of IZTO, in order to increase the water vapor barrier property of the second transparent electrical layer and to consider the light transmittance of the second transparent electrical layer, the second transparent surface electrode layer 9 may be designed to have a double-layer structure including a first surface electrode layer 91 including IZTO and a second surface electrode layer 92 including ITO. The first surface electrode layer 91 comprises a continuous first ITO region 911 and a plurality of first IZTO regions 912 which are positioned in the first ITO region 911 and distributed in a matrix; the second surface electrode layer 92 includes a continuous second IZTO region 922 and a plurality of second ITO regions 921 located in the second IZTO region 922 and distributed in a matrix.

That is, the transparent surface electrode layer 9 contains IZTO and ITO at the same time, so that the transparent surface electrode layer can have both good water vapor barrier property of IZTO and good light transmittance of ITO, and the water vapor barrier property can be improved without affecting the light transmittance of the transparent surface electrode layer 9. The relative positions of the first surface electrode layer 91 and the second surface electrode layer 92 may be adjusted so that the first surface electrode layer 91 is close to the buffer layer 7 or the second surface electrode layer 92 is close to the buffer layer 7.

As for the structure of the first surface electrode layer 91, specifically, it may include a continuous first ITO region 911 and a plurality of first IZTO regions 912 located in the first ITO region 911 and distributed in a matrix, and similarly, the second surface electrode layer 92 may include a continuous second IZTO region 922 and a plurality of second ITO regions 921 located in the second IZTO region 922 and distributed in a matrix, so that, from the perspective of the transparent surface electrode layer 9 as a whole, it has both an IZTO structure and an ITO structure, and the structure is relatively uniform, thereby being capable of achieving an improvement in moisture barrier property without affecting the light transmittance of the transparent surface electrode layer 9.

In order to further improve the light transmittance and the water vapor barrier property of the barrier CIGS solar cell, the first ITO region 911 and the second ITO region 921 are projected on the solar cell substrate as a continuous plane, and the first IZTO region 912 and the second IZTO region 922 are projected on the solar cell substrate as a continuous plane. That is, the first ITO region 911 and the second ITO region 922 have the same shape and size and are located at the corresponding positions, and the first IZTO region 912 and the second ITO region 921 have the same shape and size and are located at the corresponding positions, so that the first IZTO region 912 and the second IZTO region 922 can form a complete film structure with good water vapor barrier property, thereby further improving the light transmittance and water vapor barrier property of the barrier CIGS solar cell.

In order to improve the uniformity of the entire transparent surface electrode layer 9, the ratio of the area of the first ITO region 911 to the total area of the plurality of first IZTO regions 912 may be controlled to be 1.4 to 1.7, and the ratio of the area of the same second IZTO region 922 to the total area of the plurality of second ITO regions 921 may be controlled to be 1.4 to 1.7.

Considering that the size and distribution density of the first IZTO area 912 and the second ITO area 921 also affect the uniformity of the transparent surface electrode layer 9 as a whole, when the first IZTO area 912 and the second ITO area 921 are square, the ratio of the gap between two adjacent first IZTO areas 912 to the side length of the first IZTO area 912 can be controlled within 0.5-0.8, and similarly, the ratio of the gap between two adjacent second ITO areas 921 to the side length of the second ITO area 921 can be controlled within 0.5-0.8.

In view of the fact that the CIGS solar cell needs to be exposed to the external environment for a long time and is sensitive to its own structure, especially for the transparent surface electrode layer 9, which is located on the surface of the CIGS solar cell and is exposed to sunlight for a long time, the transparent surface electrode layer is easily deformed under high temperature or external impact, and thus the overall operation stability of the CIGS solar cell is affected, therefore, a shape memory alloy fiber 93 layer may be disposed between the first surface electrode layer 91 and the second surface electrode layer 92. The shape memory alloy fiber 93 has the functions of self-diagnosis, self-adaptation, self-repair, and the like. When the transparent surface electrode layer 9 is deformed at a high temperature or by external impact, the shape memory alloy fibers 93 can restore the transparent surface electrode layer 9 to an original state before the deformation, thereby reducing the deformation amount of the transparent surface electrode layer 9, improving the overall operation stability of the CIGS solar cell, and prolonging the service life of the CIGS solar cell.

In order to reduce the influence of the addition of the shape memory alloy fiber 93 layer on the light transmittance, the shape may be a mesh shape. In this way, sunlight can enter the CIGS solar cell through the shape memory alloy fiber 93 layer, and only the grid line portions affect the sunlight, so that the effect of the addition of the shape memory alloy fiber 93 layer on the light transmittance can be minimized.

Illustratively, the grid lines of the layer of grid-shaped shape memory alloy fibers 93 may coincide with connecting lines of the first ITO region 911, the second ITO region 921, the first IZTO region 912, and the second IZTO region 922. This is because, since the connecting lines of the first ITO region 911, the second ITO region 921, the first IZTO region 912, and the second IZTO region 922 are the junctions of the four regions, the light transmittance is relatively poor here in consideration of the influence of the processing process and the material, the grid lines overlap with the connecting lines, and the addition of the grid-like shape memory alloy fiber 93 layer affects only the light transmittance of the connecting line portion having relatively poor light transmittance, and does not affect other portions of the transparent surface electrode layer 9, whereby the influence of the addition of the shape memory alloy fiber 93 layer on the light transmittance can be further reduced.

Considering that the electrode of the transparent surface electrode layer 9 generates heat due to resistance in the actual working process, the transparent surface electrode layer 9 may be doped with nano silver (Ag) particles, because the thermal conductivity of Ag is better than that of ITO and IZTO, and the doping of Ag in the transparent surface electrode layer 9 can improve the overall thermal conductivity of the transparent surface electrode layer 9, so that the heat generated by the electrode can be diffused into the environment more quickly, and the damage of the electrode due to resistance heating is reduced. Meanwhile, it is worth noting that the transparent surface electrode layer 9 has a high requirement on light transmittance, and in order to reduce the influence of Ag doping on the light transmittance of the transparent surface electrode layer 9, Ag nanoparticles can be used for doping, and the light absorption of the nano-sized Ag particles is small.

In order to further improve the photoelectric properties and stability of the transparent surface electrode layer 9, zirconium (Zr) may be doped therein.

In consideration of energy conservation and environmental protection and reduction of production cost, the buffer layer 7 is made of the InS and InSe composite buffer layer 7, the composite buffer layer 7 can form a band gap between the third CIGS absorption layer 63 and the intrinsic zinc oxide high-impedance layer 8, the number of current carriers is reduced, and the InS and InSe composite buffer layer 7 does not contain compounds such as CdS and the like, so that the environment is protected, the cost is reduced, the production process equipment is simple, the energy consumption is low, the production period is short, and the like.

The InS and InSe composite buffer layer 7 at least comprises two sequentially alternating InS layers and InSe layers, and the InS layers and the InSe layers both contain sodium. For example, the InS and InSe composite buffer layer 7 includes a first InS layer, a first InSe layer, a second InS layer, and a second InSe layer; the upper end face of the first InS layer is close to the intrinsic zinc oxide layer, and the lower end face of the second InSe layer is close to the first CIGS absorber layer 61; the first InS layer, the first InSe layer, the second InS layer and the second InSe layer all contain sodium.

In this embodiment, "sodium" may be pure metal sodium, sodium ion, or sodium in a compound. For example, Na may be used₂Se、Na₂S、Na₂SeO₃Or NaNbO₃Sodium in (1), preferably Na₂Se、Na₂And S. Since S and Se are contained in the indium sulfide layer and the indium selenide layer, respectively, Na is used₂Se and Na₂S does not introduce new impurities.

In order to increase the absorption of sunlight to the maximum extent, an anti-reflection layer 113 is provided above the transparent surface electrode layer 9, and the anti-reflection layer 113 is used for reducing the reflection of light in the ITO low-resistance layer. The anti-reflection layer 113 of the present invention is MgF₂The thickness of the anti-reflection layer 113 can be adjusted according to actual production requirements.

In order to effectively prevent impurity elements in the substrate from entering the absorption layer 6, a barrier layer is arranged between the polyimide film and the back electrode layer 2, the barrier layer is of a three-layer structure or more than three-layer structure, and each layer in the three-layer structure of the barrier layer is respectively one of silver, copper or titanium.

In one possible design, the barrier layers include a first sub-barrier layer, a second sub-barrier layer and a third sub-barrier layer, wherein the first sub-barrier layer is close to the back electrode layer 2, and the third sub-barrier layer is close to the polyimide film substrate; in order to improve the bonding force between the barrier layer and the polyimide film and between the barrier layer and the back electrode layer 2 and to prevent impurities from entering the absorption layer 6 from the substrate, the first sub-barrier layer and the third sub-barrier layer are both made of titanium, the second sub-barrier layer arranged in the middle is made of titanium nitride, and the thickness of the diffusion barrier layer is 1200 nm. Since the barrier layer can be prepared on the polyimide film by using a conventional magnetron sputtering method, the specific preparation process is not described herein.

It should be noted that the alkali metal doped composite layer 4 of the present invention may be a Na doped composite layer structure; the Na doping amount in the Na-doped composite layer structure can realize gradient increase of the Na doping amount in an equal difference and equal ratio mode; for example, the Na-doped composite layer structure comprises a first Na-doped layer, a second Na-doped layer and a third Na-doped layer, and the Na doping amount of the first Na-doped layer is greater than the second Na doping amount and greater than the third Na doping amount; under the condition that the Na doping amount is not changed, compared with a uniformly distributed Na doping layer, the alkali metal doped flexible substrate CIGS cell provided by the embodiment has a larger Na doping amount close to the third CIGS absorption layer 63, so that the Na concentration difference between the first Na doping layer and the third CIGS absorption layer 63 is increased, the infiltration amount and the infiltration depth of Na infiltrating into the CIGS layer can be further increased, and the utilization rate of Na is further increased.

In practical applications, although the thickness of the alkali metal-doped composite layer 4 is small, when the doping amount gradient of Na in the alkali metal-doped composite layer 4 increases, Na atoms may not be uniformly distributed in the alkali metal-doped composite layer 4 even after being stored for a long time, that is, the alkali metal-doped composite layer 4 still has the Na doping amount gradient.

According to the invention, Na is selected as the main alkali metal which is diffused into the CIGS layer, so that the defect density of the CIGS layer is greatly reduced compared with the defect density of the CIGS layer which is made of other alkali metals, and the carrier concentration is greatly improved, thereby the cell has higher photoelectric conversion efficiency.

Example 2

The embodiment provides a preparation method of a flexible substrate CIGS solar cell, which comprises the following steps:

s1, preparing a back electrode layer 2 on the solar cell flexible substrate 1;

firstly, preparing a back electrode layer 2 on a substrate; the substrate is made of polyimide or a composite substrate of polyimide and glass or a composite substrate of polyimide and a stainless steel sheet, and molybdenum (Mo) metal with the thickness of 0.8 mu m is deposited on the substrate by a magnetron sputtering method to serve as the back electrode layer 2.

S2, preparing a reflecting layer 3 and an alkali metal doped composite layer 4 on the back electrode layer 2;

s3, depositing the first CIGS absorber layer 61 on the back electrode layer 2 by using a multi-step sputtering method, and depositing the second CIGS absorber layer 62 and the third CIGS absorber layer 63 on the first CIGS absorber layer 61;

s4, preparing a buffer layer 7 on the third CIGS absorber 63;

in this step, a buffer layer 7 is prepared on the absorber layer 6: by vacuum magnetron sputtering method using In₂Se₃Or ZnS alloy target, sputter-depositing In₂Se₃Or ZnS buffer layer 7, the working pressure of vacuum magnetron sputtering is 1-5 multiplied by 10^-3Torr was introduced and Ar gas was introduced, and the temperature of the substrate was maintained at room temperature. The In2Se3 or ZnS buffer layer 7 is deposited to a thickness of 80 to 120 nm. By mixing Na₂Se source and In₂Se₃Source, Na₂S source and In₂S₃The sources are alternately arranged and the substrate deposited with the back electrode layer 2 and the light absorbing layer 6 is first transported over Na₂Se source and In₂Se₃Source, re-transport over Na₂S source and In₂S₃The deposition of the indium selenide layer and the indium sulfide layer can be finished at one time, and the production efficiency is improved.

S5, preparing an intrinsic zinc oxide high-resistance layer 8 on the buffer layer 7;

in this S5 step, the intrinsic zinc oxide high-resistance layer 8 is prepared on the buffer layer 7: by utilizing a radio frequency vacuum magnetron sputtering method, the target material is intrinsic zinc oxide (ZnO), the working pressure of the radio frequency vacuum magnetron sputtering is 1-5 multiplied by 10 < -3 > Torr, the working frequency is 400K-2 MHz, Ar gas is introduced, and the temperature of the substrate is kept at room temperature. The intrinsic zinc oxide high resistance layer 8 is deposited to a thickness of 0.1 to 0.5 μm.

S6, preparing indium tin oxide (In) on the intrinsic zinc oxide high-resistance layer 8₂O₃:SnO₂) Thin film low resistance layer: the target material is indium tin oxide (In) by using a vacuum direct current magnetron sputtering method₂O₃:SnO₂)，In₂O3:SnO₂The mass ratio of (A) is 9:1, the working pressure of vacuum direct current magnetron sputtering is 1-5 x 10-3Torr, and 2-5% of O is doped₂The temperature of the substrate was kept at room temperature. The deposition thickness of the low resistance layer of indium tin oxide film is 0.3 to 0.8 μm.

S7, preparing an aluminum electrode on the indium tin oxide thin film low-impedance layer, and preparing an anti-reflection layer 113 on the Al electrode 10;

and preparing an Al electrode by using an Al target material through a sputtering method, and finally obtaining the copper indium gallium selenide thin-film solar cell.

It is emphasized that, when the transparent surface electrode layer 9 of the present invention includes a first transparent electrode layer and a second transparent electrode layer, the method of forming the transparent surface electrode layer 9 includes the steps of: forming a first surface electrode layer 91 and a second surface electrode layer 92 on the surface of the buffer layer 7; the first surface electrode layer 91 is produced by the following method: an ITO layer is formed by a sputtering process, a plurality of IZTO accommodating grooves distributed in a matrix form are formed on the ITO layer by an etching process, a first IZTO area 912 is formed in the plurality of IZTO accommodating grooves by the sputtering process, and the non-etched part of the ITO layer is a first ITO area 911. The second surface electrode layer 92 is prepared by the following method: the method comprises the steps of forming an IZTO layer by adopting a sputtering process, forming a plurality of ITO containing grooves which are distributed in a matrix mode on the IZTO layer by adopting an etching process, forming a second ITO area 921 in the plurality of ITO containing grooves by adopting the sputtering process, wherein the non-etched part of the IZTO layer is a second IZTO area 922.

When the shape memory alloy fiber 93 layer is disposed between the first surface electrode layer 91 and the second surface electrode layer 92, the method for forming the surface electrode layer includes the following steps:

step a: laying shape memory alloy fibers 93 on the surface of the first surface electrode layer 91;

step b: carrying out hot pressing on the shape memory alloy fibers 93, so that part of the shape memory alloy fibers 93 are embedded into the first surface electrode layer 91, and obtaining a shape memory alloy fiber 93 layer;

step c: a second surface electrode layer 92 is formed on the surfaces of the first surface electrode layer 91 and the shape memory alloy fiber 93.

Alternatively, the method for forming the surface electrode layer includes the steps of:

step a': laying shape memory alloy fibers 93 on the surface of the second surface electrode layer 92;

step b': carrying out hot pressing on the shape memory alloy fibers 93, so that part of the shape memory alloy fibers 93 are embedded into the second surface electrode layer 92, and obtaining a shape memory alloy fiber 93 layer;

step c': the first surface electrode layer 91 is formed on the surfaces of the second surface electrode layer 92 and the shape memory alloy fiber 93.

The shape memory alloy fibers 93, the first surface electrode layer 91 and the second surface electrode layer 92 can be tightly combined by adopting a hot-pressing process, so that the phenomenon that gaps are formed among the shape memory alloy fibers 93, the first surface electrode layer 91, the shape memory alloy fibers 93 and the second surface electrode layer 92 to influence the overall performance of the CIGS solar cell is avoided. It should be noted that the two methods are substantially the same, and only the relative positions of the first surface electrode layer 91 and the second surface electrode layer 92 are appropriately adjusted.

In order to make the bonding of the shape memory alloy fiber 93 to the first surface electrode layer 91 and the second surface electrode layer 92 tighter, the shape memory alloy fiber 93 may be further subjected to a pretreatment including the steps of: and sequentially grinding and polishing the surface of the shape memory alloy fiber 93, carrying out acid etching for 20-30 s, cleaning and drying. The shape memory alloy fiber 93 is polished to remove an oxide layer on the surface of the shape memory alloy fiber 93, so that the next step of acid etching is more sufficient. The acid etching process is substantially a process of increasing the surface area of the shape memory alloy fiber 93, and the acid etched shape memory alloy fiber 93 is fully contacted in the subsequent hot pressing process, so that the first surface electrode layer 91, the second surface electrode layer 92 and the shape memory alloy fiber 93 are more tightly combined.

For the hot pressing process, the hot pressing temperature, the hot pressing pressure and the hot pressing time are important process conditions for fully stretching the shape memory alloy fibers 93, the hot pressing temperature is preferably 800-900 ℃, the hot pressing pressure is preferably 100-120 MPa, and the hot pressing time is preferably 3-4 h.

Example 3

As shown in fig. 9, 10 and 11, in the implementation of the present invention, the encapsulation structure 12 of the flexible solar thin film cell is a rectangular encapsulation structure 12, and includes a protection film, a structural film and a back film which are compressed from top to bottom, in general, for convenience of processing, the flexible substrate CIGS solar cell is generally made into a rectangular shape, and the core object of encapsulation is the flexible substrate CIGS solar cell, so the encapsulation structure 12 is a rectangular shape. The size of the structured film and the flexible substrate CIGS solar cell are the same; the size of the back film is larger than that of the flexible substrate CIGS solar cell; the protective film comprises a main body and side portions, the main body is the same as the flexible substrate CIGS solar cell in size, the side portions are arranged on four sides of the main body and are integrated with the main body into a whole, and the side portions are sealed and tightly cover the side faces of the structural film and the flexible substrate CIGS solar cell and are tightly pressed with the back film. In the package structure 12, the bulk of the protective film, the structural film and the flexible substrate CIGS solar cell are used as the core of the main lamination package, and the sizes need to be equal; the edge of the protective film is used for packaging the side edge, so that the width of the edge is equal to that of the corresponding side edge, the length of the edge is greater than the thickness of the solar thin film cell, and the excess part is used for being bonded with the back film to realize the fixation of the edge and the internal packaging.

The packaging structure 12 of the embodiment of the invention is equivalent to packaging the main illumination surface and the side surface of the solar thin film battery by using the protective film at the same time, a special side packaging material is not needed, the packaging structure 12 of the solar thin film battery is simplified, and in addition, the protective film is a whole, so that the bonding surface of the packaging structure 12 is reduced, the risk of water permeation of the packaging structure 12 can be reduced, the service life of the solar thin film battery is further prolonged, and the requirement of the solar thin film battery on the use environment is reduced.

In order to obtain the greatest photoelectric conversion efficiency of the solar thin-film battery on the premise of ensuring the water blocking function of the packaging structure 12, in the embodiment of the invention, the protective film is an ETFE film 121; the structural film is an EEA film 123; the back film is a two-layer film, one layer in contact with CIGS is DNP film 127 and the other layer is PET film 128.

The ETFE film 121 is a transparent water blocking film, and considering that the ETFE film is used for flexible packaging, the structural strength of the ETFE film is obviously superior to that of common fluororesin transparent films such as PFA and FEP, and although the relevant performance of the PCTFE film is slightly better than that of the ETFE film 121, the phase property of the PCTFE film with other materials is poor, the adhesion with the structural film after lamination is not facilitated, and the light transmission, the structural strength, the packaging effect and the water blocking effect are comprehensively considered.

The EEA film 123 is a type of polyolefin film, and is characterized by excellent toughness and flexibility, and good light transmittance, and in the embodiment of the present invention, the solar thin film cell needs to have good deformation performance, so that the use of the EEA film 123 as a structural film mainly providing structural performance is effective, and has strong resistance to stress rupture, impact, and bending fatigue. In addition, EEA film 123 is free of corrosive degradation products, which can ensure that encapsulation structure 12 is not corroded due to internal degradation.

In addition to ensuring structural strength, the backing film must also have good water-blocking properties, and must also have good adhesive properties as the primary object of bonding other layers. The DNP film 127 binder has good phase properties, and can ensure long-term, highly durable adhesion characteristics, and thus, the durability of the solar thin film cell. The PET film 128 has good structural strength and excellent water blocking performance, and can still maintain the original various performances in extreme environments such as moist heat and dry heat, and thus is very suitable for being used as an outer layer film of a back film.

In addition to optimizing the design of the films of each layer, embodiments of the present invention also optimize the design of the adhesive between the layers. Specifically, the main body of the ETFE film 121 and the EEA film 123 are adhered by the POE adhesive 122; the EEA film 123 and the flexible substrate CIGS solar cell are adhered through EVA glue 124; the CIGS battery power supply 125 and the DNP film 127 are adhered through PVB glue 126; the edge of the ETFE film 121, the side of the structural film, the side of the flexible substrate CIGS solar cell, and the back film are all adhered by POE adhesive 122.

The POE adhesive 122 has good weather resistance and ultraviolet aging resistance, good adhesion and light transmittance, good phase property with the materials in the embodiment of the present invention, can be firmly and stably bonded, and has a certain water resistance, so in the embodiment of the present invention, the POE adhesive 122 is used for bonding with the ETFE film 121.

The EVA adhesive 124 is also a transparent adhesive, and has the disadvantages of higher water vapor transmission rate and water absorption rate and lower cost compared with the POE adhesive 122. In the embodiment of the present invention, since the ETFE film 121 and the POE adhesive 122 are present to perform double-layer water blocking, a good waterproof effect can be achieved, and therefore, from the viewpoint of saving cost, the EEA film 123 and the flexible substrate CIGS solar cell are adhered by the EVA adhesive 124.

The PVB adhesive 126 is also one of the photovoltaic materials, the light transmittance is slightly lower than that of the POE adhesive 122, the cost is relatively low, the PVB adhesive 126 can be used in the back film because the back film also needs to have good waterproof performance and is also not suitable for the use of the EVA adhesive 124, and the PVB adhesive 126 is also used in the back film instead of the POE adhesive 122 because the PVB adhesive 126 has good weather resistance and the back film does not need to have too high light transmittance.

In order to ensure that the solar thin film cell can be normally used, current of two electrodes of the flexible substrate CIGS solar cell needs to be led out, in the embodiment of the invention, the surface electrode layer and the back electrode layer 2 of the CIGS cell power supply 125 are respectively and electrically connected with the cell electrodes arranged on the back film through wires, and the wires are wired at the connecting surface between the edge and the back film, that is, the wires are sandwiched between the edge and the back film.

In the embodiment of the present invention, the light incident surface is required to have good light transmittance because of the solar cell, and specifically, the ETFE film 121, the EEA film 123, the POE adhesive 122, and the EVA adhesive 124 are all transparent materials.

Example 4

As shown in fig. 11, an encapsulation tool for a flexible solar thin film cell encapsulation structure 12 is used for processing the encapsulation structure 12 in example 3; the packaging tool comprises a first tool and a second tool, wherein the first tool and the second tool are at least provided with a group of parallel surfaces, one surface is a plane, and the other surface is provided with a square groove; the size of the groove of the first tool is equal to the size of the EEA film 123, the EVA glue 124 and the flexible substrate CIGS solar cell of the packaging structure 12; the size of the recess of the second tooling is equal to the overall size of the package structure 12. The encapsulation structure 12 in example 3 corresponds to a CIGS solar cell with a structural film and a flexible substrate, using a protective film and a back film. In the embodiment of the invention: the first tool is used for completing lamination of a structural film and a flexible substrate CIGS solar cell and only comprises lamination bonding between layers; the second tooling is used to complete lamination of the protective and back film clad structural film and flexible substrate CIGS solar cells, including layer-to-layer lamination bonds and edge-to-side bonds.

The embodiment of the invention is mainly used for realizing the packaging structure 12 of the embodiment 3, corresponding materials are sequentially placed in the grooves for lamination processing to prepare the packaging structure 12 of the embodiment 1, the lamination combination of the packaging structure 12 of the solar thin film cell is realized through the square groove of the packaging tool, the dislocation among layers is prevented, the packaging quality of the solar thin film cell is ensured, and the yield is improved.

In order to prevent the laminated material from adhering to the packaging tool, in the embodiment of the invention, the material of the packaging tool is the same as that of the pressure head of the laminating machine, the pressure head of the laminating machine is generally made of a material which is not easy to adhere by the laminated material, and the material of the packaging tool is the same as that of the pressure head for the same reason so as to prevent the laminated object from adhering to the packaging tool.

Example 5

The invention also provides a packaging method of the flexible solar thin film battery, which is used for packaging the flexible solar thin film battery by using the packaging tool in the embodiment 4 and manufacturing the packaging structure 12 in the embodiment 3;

the packaging method specifically comprises the following steps:

s1, processing a flexible substrate CIGS solar cell, where the size of the flexible substrate CIGS solar cell should be determined according to a design size, and belongs to preset parameters, and similarly, the sizes of the ETFE film 121, the POE adhesive 122, the EEA film 123, the EVA adhesive 124, and the PVB adhesive 126 also belong to preset parameters, and need to be determined according to a processing target, it should be noted that the length of the edge of the ETFE film 121 is greater than the thickness of the solar thin film cell, and the sizes of the DNP film 127 and the PET film 128 need to be greater than the size of the flexible substrate CIGS solar cell, and an excessively long portion of the edge of the ETFE film 121 can be completely bonded to the DNP film 127;

s2, placing the groove of the first tool upwards, placing the EEA film 123, the EVA adhesive 124 and the flexible substrate CIGS solar cell in the groove in sequence, aligning all materials when placing all the materials, and placing the materials in the groove of the first tool to ensure that the EEA film 123 and the flexible substrate CIGS solar cell can be laminated to form an integral structure;

s3, placing the first tool in a laminating machine, and performing high-temperature pressing to form an integral structure;

s4, cooling the first tool to room temperature, and taking out the integrated structure pressed in the step S3;

s5, placing the groove of the second tool upwards, placing an ETFE film 121, POE glue 122, the integral structure of the previous step, PVB glue 126, a DNP film 127 and a PET film 128 in the groove in sequence, wherein the main body of the ETFE film 121 is in close contact with and aligned with the bottom surface of the groove of the second tool, and the other parts of the ETFE film are aligned with the main body of the ETFE film 121; the edge of the ETFE film 121 is in close contact and alignment with the side wall of the second tool groove, and POE adhesive 122 is added to the inner side of the edge of the ETFE film 121;

s6, placing the second tool in a laminating machine, and performing high-temperature pressing to form an integral structure;

s7, cooling the second tool to room temperature, and taking out the integrated structure pressed in the step S6;

and S8, cutting the back film into a preset size, and finishing the packaging of the flexible substrate CIGS solar thin film cell.

According to the embodiment of the invention, the traditional one-step lamination packaging is optimized into two-step lamination packaging, so that not only can a good lamination effect between layers of the solar thin film battery packaging structure 12 be ensured, but also the side edge packaging effect of the packaging structure 12 can be ensured, the packaged solar thin film battery can form a whole, further the light transmittance and the battery efficiency are improved, the side edge is prevented from deliquescence to a certain extent, the service life of the solar thin film battery is prolonged, and the service environment adaptability of the solar thin film battery is improved.

The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are included in the scope of the present invention.

Claims

1. A flexible substrate CIGS solar cell is characterized by comprising a substrate, and a back electrode layer, a reflecting layer, an absorbing layer, a first buffer layer, a high-impedance layer and a transparent surface electrode layer which are sequentially stacked on the flexible substrate; the high-impedance layer is an intrinsic zinc oxide high-impedance layer;

an alkali metal doped composite layer is arranged between the reflecting layer and the absorbing layer, at least one channel is correspondingly arranged on the alkali metal doped composite layer and the reflecting layer, a back electrode layer is arranged at the bottom of the channel, a Mo electrode thin film layer is arranged on the side wall of the channel, and a part of the absorbing layer is filled in the channel and is in direct physical contact with the back electrode layer; one side of the Mo electrode film layer forms a channel side wall, and the other side of the Mo electrode film layer is adjacent to the side surfaces of the alkali metal doped composite layer and the reflecting layer;

the alkali metal is sodium.

2. The flexible substrate CIGS solar cell as recited in claim 1 wherein the absorber layer is divided into a first CIGS absorber layer, a second CIGS absorber layer and a third CIGS absorber layer having sequentially increasing band gap widths, a portion of the third CIGS absorber layer filling the channel and being in physical contact with the back electrode layer.

3. The flexible substrate CIGS solar cell as recited in claim 2, wherein the back electrode layer is a Mo back electrode composite structure, the Mo back electrode composite structure comprises a first sub Mo electrode layer, a first stress buffer layer, a second sub Mo electrode layer, a second stress buffer layer and a third sub Mo electrode layer in sequence from top to bottom, and the thicknesses of the first sub Mo electrode layer, the second sub Mo electrode layer and the third sub Mo electrode layer are reduced in sequence.

4. Flexible substrate CIGS solar cell according to claim 3,

the first stress buffer layer and the second stress buffer layer are both Ag films, and the thickness of the first stress buffer layer is larger than that of the second stress buffer layer.

5. The flexible substrate CIGS solar cell as claimed in claim 3 or 4, wherein the substrate is made of polyimide, and the polyimide is in contact with the third sub-Mo electrode layer.

6. Flexible substrate CIGS solar cell according to claim 5,

the transparent surface electrode layer comprises an ITO low-impedance layer, and an Al electrode is arranged on the ITO low-impedance layer.

7. The flexible substrate CIGS solar cell as claimed in claim 6, wherein the transparent surface electrode layer is an ITO-Ag-ITO transparent thin film layer with an Al electrode disposed thereon.

8. The flexible substrate CIGS solar cell as claimed in claim 7 wherein said buffer layer is a composite buffer layer of InS and InSe; the InS and InSe composite buffer layers are alternately arranged.

9. Flexible substrate CIGS solar power as claimed in claim 8The cell is characterized in that an anti-reflection layer is arranged above the transparent surface electrode layer, and the anti-reflection layer is MgF₂A film, the anti-reflection layer for reducing reflection of light in the ITO low resistance layer.

10. The flexible substrate CIGS solar cell as recited in claim 8, characterised in that a barrier layer is provided between the polyimide film and the back electrode layer, said barrier layer comprising at least three layers, said three layers being a silver, copper or titanium layer respectively; the barrier layer is used for blocking impurity elements in the substrate from entering the absorption layer.

11. The flexible substrate CIGS solar cell as recited in claim 10 wherein the barrier layer comprises a first sub-barrier layer in contact with the back electrode layer, a second sub-barrier layer and a third sub-barrier layer in contact with the polyimide film substrate.

12. The flexible substrate CIGS solar cell as recited in claim 11 wherein the alkali metal doped composite layer is a Na doped composite layer structure;

the Na-doped composite layer structure comprises a first Na doped layer, a second Na doped layer and a third Na doped layer, and the Na doping amount of the first Na doped layer is larger than the second Na doping amount and larger than the third Na doping amount.

13. A method for the production of flexible substrate CIGS solar cells as claimed in any one of claims 1 to 12, characterised by the following steps:

s1, preparing a back electrode layer on the solar cell substrate;

s4, preparing a buffer layer on the first CIGS absorption layer; preparing an intrinsic zinc oxide high-impedance layer on the buffer layer; preparing an indium tin oxide thin film low-impedance layer on the intrinsic zinc oxide high-impedance layer;

14. An encapsulation structure for encapsulating the flexible substrate CIGS solar cell as claimed in any of the claims 1 to 12, characterised in that it is rectangular, comprising a protective film, a structural film and a back film, compacted from top to bottom;

the structural film and the flexible substrate CIGS solar cell are the same size;

the backsheet is larger in size than the flexible base CIGS solar cell.

15. The encapsulation structure for encapsulating flexible base CIGS solar cells as claimed in claim 14, wherein said protective film comprises a body of the same size as the flexible base CIGS solar cell and edges disposed on four sides of the body and integral with the body, said edges hermetically sealing against the sides of the structural film and flexible base CIGS solar cells and compressing against the back film.