CN105097980A - Thin film solar cell and manufacturing method thereof - Google Patents

Abstract

The application provides a thin-film solar cell, which comprises a metal substrate, a first isolation layer arranged on the metal substrate, a second isolation layer arranged on the first isolation layer, a back electrode layer arranged on the second isolation layer and a copper indium gallium selenide light absorption layer arranged on the back electrode layer, wherein the first isolation layer and the second isolation layer are used for preventing metal elements in the metal substrate from entering the copper indium gallium selenide light absorption layer, and the second isolation layer comprises sodium elements, wherein the sodium elements can be supplemented to the copper indium gallium selenide light absorption layer to repair point defects caused by selenium deficiency in the copper indium gallium selenide light absorption layer. In addition, the application also provides a method for manufacturing the thin film solar cell.

Description

Thin film solar cell and manufacturing method thereof

technical field

The present application relates to the field of solar cells, in particular to a copper indium gallium selenide thin film solar cell and a manufacturing method thereof.

Background technique

Copper indium gallium selenide (Cu(In,Ga)Se ₂ , referred to as CIGS) thin-film solar cells have developed rapidly in the last 30 years, and have the characteristics of low cost, high efficiency and good stability. CIGS thin-film solar cells are multi-layer thin-film laminated structures, which generally include a substrate, a back electrode layer, a light-absorbing layer (selenized after sputtering, or a P-type semiconductor CuInxGa(1-x)Se2 deposited by co-evaporation), and a buffer layer (such as CdS produced by water bath method), intrinsic zinc oxide layer (intrinsic zinc oxide produced by sputtering method) and window layer (aluminum-doped zinc oxide produced by sputtering method). There is also a grid electrode on the outermost light incident surface, which is used to extract photocurrent.

Since CIGS is a P-type semiconductor, there are often point defects in it, which generally manifest as selenium deficiency. Such defects can be repaired by introducing sodium atoms into the spot, and the diffusion of sodium can optimize the performance of the CIGS light-absorbing layer. In the prior art, a layer of sodium fluoride is usually added between the back electrode layer and the CIGS light-absorbing layer to supplement a trace amount of sodium element to the light-absorbing layer. Sodium fluoride film is generally obtained by thermal evaporation, the thickness is about 10nm, the deposition speed is slow, and it is difficult to deposit uniformly. Moreover, sodium fluoride is highly toxic and corrosive, which increases unsafe factors in the production process.

Contents of the invention

The present application provides a thin-film solar cell capable of at least partially improving the defects in the above-mentioned prior art.

According to one embodiment of the present application, a thin-film solar cell is provided, which includes a metal substrate, a first isolation layer disposed on the metal substrate, a second isolation layer disposed on the first isolation layer, and a second isolation layer disposed on the second isolation layer. The back electrode layer on the two isolation layers, the copper indium gallium selenide light absorption layer arranged on the back electrode layer, wherein the first isolation layer and the second isolation layer are used to prevent metal elements in the metal substrate from entering the copper indium gallium selenide The light absorbing layer, and the second isolation layer includes sodium element, and the sodium element is supplemented to the CIGS light absorbing layer.

According to another embodiment of the present application, there is provided a method for manufacturing a thin film solar cell, comprising: providing a metal substrate; forming a first isolation layer on the metal substrate by sputtering; forming a first isolation layer on the first isolation layer by sputtering generate a second isolation layer by sputtering on the second isolation layer; and form a copper indium gallium selenide light absorbing layer on the back electrode layer; where the first isolation layer and the second isolation layer are used In order to prevent metal elements in the metal substrate from entering the CIGS light-absorbing layer, the second isolation layer includes sodium element, and the sodium element is supplemented to the CIGS light-absorbing layer.

As mentioned above, in the thin-film solar cell provided by the present application, due to the double-layer isolation layer, it can better prevent metal elements in the metal substrate, especially iron elements, from entering the copper indium gallium selenide light absorption layer, thereby The semiconductor properties of the light absorbing layer are protected from being damaged, and the conversion efficiency is not reduced. Moreover, since the second isolation layer contains sodium element, it is also possible to supplement sodium element to the light absorbing layer while blocking iron element to optimize the performance of the CIGS light absorbing layer.

Description of drawings

1 is a schematic diagram of a multilayer structure of a thin film solar cell according to an embodiment of the present application;

2 is a flowchart of a method for manufacturing a thin film solar cell according to another embodiment of the present application; and

FIG. 3 is a schematic diagram illustrating the efficiency comparison between a thin film solar cell according to an embodiment of the present application and a thin film solar cell in the prior art.

Detailed ways

For a better understanding of the application, various aspects of the application will be described in more detail with reference to the accompanying drawings. It should be understood that the drawings and detailed description are only descriptions of preferred embodiments of the present application, and are not intended to limit the scope of the present application in any way.

FIG. 1 shows a schematic diagram of a multilayer structure of a thin film solar cell 1000 according to an embodiment of the present application. As shown in FIG. 1, a thin film solar cell 1000 includes a metal substrate 100, a first isolation layer 200 disposed on the metal substrate 100, a second isolation layer 300 disposed on the first isolation layer 200, and a second isolation layer 300 disposed on the second isolation layer. A back electrode layer 400 on layer 300 and a copper indium gallium selenide (CIGS) light absorbing layer 500 disposed on the back electrode layer 400 .

The metal substrate 100 may be a flexible substrate, wherein the material constituting the flexible metal substrate generally includes one or more of metals such as stainless steel, pure titanium, and aluminum. Flexible metal substrates have the advantage of being lightweight and bendable. In this embodiment, the metal substrate 100 may be a stainless steel substrate.

In one embodiment, the first isolation layer 200 may be an insulator isolation layer, which includes, for example, one or more of an aluminum oxide layer, a silicon oxide layer, a chromium layer, and a pure titanium layer. The first isolation layer 200 can be formed on the metal substrate 100 by radio frequency magnetron sputtering process, and its thickness can be, for example, 1-2 microns in one embodiment. The first isolation layer 200 can also be, for example, an aluminum oxide layer. The first isolation layer 200 can be used to prevent metal elements in the metal substrate 100 , especially iron elements from entering the CIGS light absorbing layer.

In one embodiment, the second isolation layer 300 may be an insulator isolation layer including, for example, a thin layer of sodium glass (SLGTF). The second isolation layer 300 can be formed on the first isolation layer 200 by, for example, radio frequency magnetron sputtering process, and its thickness can generally be 200-300 nm. In this embodiment, the second isolation layer 300 is a thin layer of soda-containing glass deposited by sputtering target material soda-lime glass. The second isolation layer 300 can not only be used to further prevent metal elements in the metal substrate 100, especially iron elements from entering the CIGS light absorbing layer, but also include sodium elements in the second isolation layer 300, wherein the sodium elements can be added to the CIGS light absorption layer. Absorbing layer to repair point defects caused by selenium deficiency in CIGS light absorbing layer.

The first isolation layer 200 and the second isolation layer 300 are produced respectively by using a layer of aluminum oxide and a thin layer of sodium-containing glass, which can make these isolation layers have good chemical stability, high deposition rate, and are compatible with the substrate and the back electrode. The thermal expansion coefficients between them are well matched, and the cost is low. Moreover, the aluminum oxide layer and the sodium-containing glass thin layer can be formed by a unified radio frequency magnetron sputtering process, and the process equipment and conditions are simple. Compared with sodium fluoride in the prior art, the thin layer of sodium-containing glass can not only prevent the iron element in the metal substrate 100 from entering the CIGS light absorption layer, but also provide CIGS with a safe, reliable, non-toxic and low-cost method. The light absorbing layer provides sodium element, thereby improving the conversion efficiency of the light absorbing layer.

In one embodiment, the back electrode layer 400 may be a metal molybdenum back electrode conductive layer, and the metal molybdenum back electrode layer may also be formed by radio frequency magnetron sputtering. The back electrode layer 400 may serve to receive positively charged carriers.

Returning to FIG. 1 , the thin film solar cell 1000 according to one embodiment of the present application may further include a buffer layer 600 disposed on the CIGS light absorbing layer 500, an intrinsic zinc oxide layer 700 disposed on the buffer layer 600, and an intrinsic zinc oxide layer disposed on the present application. Window layer 800 on zinc oxide layer 700. Wherein, the buffer layer 600 can be, for example, a cadmium sulfide (Cds) buffer layer produced by a water bath method, the intrinsic zinc oxide layer 700 can be, for example, an intrinsic zinc oxide high resistance layer generated by a sputtering method, and the window layer 800 can be, for example, Al-doped zinc oxide conductive layer produced by sputtering.

When the thin-film solar cell according to one embodiment of the present application is working, sunlight passes through the window layer 800 , the intrinsic zinc oxide layer 700 , and the buffer layer 600 , and is absorbed by the CIGS light-absorbing layer 500 to generate photogenerated carriers. Under the action of the built-in electric field, in the region of the light absorbing layer 500 close to the buffer layer 600 , carriers of different charges are separated, negative charges move to the window layer 800 , and positive charges move to the back electrode layer 400 . Thus, the solar energy is continuously converted into usable electricity.

The buffer layer 600 is used to alleviate the problem of poor lattice matching between the CIGS light-absorbing layer 500 and the window layer 800 that affects the output performance of the battery, and at the same time effectively prevent the window layer 800 from damaging the CIGS light-absorbing layer 500 during the preparation process , can eliminate the battery short circuit phenomenon caused by it. The low-power sputtered intrinsic zinc oxide layer 700 has two functions, one is to prevent sputtering damage to the buffer layer during the construction of the window layer, and the other is to prevent battery leakage by the high-resistance intrinsic zinc oxide layer. The window layer 800 is used to receive negatively charged carriers, so as to prevent the performance of the CIGS thin-film solar cell from deteriorating due to leakage problems when generating electricity.

FIG. 2 shows a flowchart of a method 2000 for manufacturing a thin film solar cell according to another embodiment of the present application. As shown in FIG. 2 , in step S201 , a metal substrate 100 is provided. As noted above, in some embodiments of the present application, stainless steel foil may be used to form the flexible metal substrate 100 .

In step S202, the first isolation layer 200 is formed on the metal substrate 100 by a sputtering method, wherein the sputtering method may include a radio frequency magnetron sputtering process. In this embodiment, a layer of Al2O3 is sputtered on the metal substrate 100 by radio frequency magnetron sputtering process as the first isolation layer 200 , the thickness of which is about 1-2 microns, for example.

In step S203 , the second isolation layer 300 is formed on the first isolation layer 200 by sputtering. In this embodiment, the target material soda-lime glass is sputtered by radio frequency magnetron sputtering process, and then a thin layer of soda-containing glass is deposited as the second isolation layer 200 with a thickness of about 200-300 nanometers. Sodium-containing glass contains very little iron, so it does not contaminate the CIGS light-absorbing layer.

In step S204 , a back electrode layer 400 is formed on the second isolation layer 300 by sputtering. In this embodiment, a molybdenum metal target is sputtered by using a radio frequency magnetron sputtering process, so as to deposit and form a molybdenum back electrode layer as the back electrode layer 400 .

In step S205 , a CIGS light absorbing layer 500 is formed on the back electrode layer 400 . Wherein, the CIGS light absorbing layer 500 may be formed by selenization after sputtering or deposition by co-evaporation. In this embodiment, the CIGS light absorbing layer is prepared by radio frequency magnetron sputtering selenization, and the thickness of the deposited light absorbing layer is about 2 microns.

In addition, as shown in FIG. 2 , in step S206 , a Cds (cadmium sulfide) buffer layer 600 is deposited on the CIGS light absorbing layer 500 using a chemical water bath method. It should be noted that other materials that can replace Cds can also be used as the buffer layer. In step S207 , an intrinsic zinc oxide layer 700 is formed on the buffer layer 600 using a sputtering method. In this embodiment, a zinc oxide ceramic target is sputtered on the cadmium sulfide buffer layer 600 using a radio frequency magnetron sputtering process, thereby depositing an intrinsic zinc oxide high resistance layer as the intrinsic zinc oxide layer 700 . In step S208 , a window layer 800 is formed on the intrinsic zinc oxide layer 700 . Wherein, an aluminum-doped zinc oxide conductive layer can be used as the window layer 800 , and an n-type graphene film can also be used as the conductive window layer 800 . The n-type graphene film includes a single layer of graphene arranged in a multilayer stack.

FIG. 3 is a schematic diagram showing the efficiency comparison between a thin film solar cell 1000 according to an embodiment of the present application and a thin film solar cell in the prior art. As can be seen from FIG. 3 , the efficiency of the thin-film solar cell 1000 provided with an aluminum oxide layer (first isolation layer 200 ) and a thin layer of sodium-containing glass (second isolation layer 300 ) according to one embodiment of the present application is significantly higher. higher than a solar cell not provided with the double-layer separator.

The exemplary embodiments of the present application are described above with reference to the accompanying drawings. Those skilled in the art should understand that the above-mentioned embodiments are only examples for the purpose of illustration, rather than limitation. Any modification, equivalent replacement, etc. made under the teaching of the present application and the protection scope of the claims shall be included in the protection scope of the present application.

Claims (13)

1. A thin-film solar cell, comprising: metal substrate; a first isolation layer arranged on the metal substrate; a second isolation layer arranged on the first isolation layer; a back electrode layer disposed on the second isolation layer; and a copper indium gallium selenide light absorbing layer arranged on the back electrode layer; Wherein, the first isolation layer and the second isolation layer are used to prevent metal elements in the metal substrate from entering the CIGS light absorbing layer, and, Wherein, the second isolation layer includes sodium element that can be supplemented to the CIGS light absorbing layer to repair point defects therein caused by selenium deficiency. 2. The thin film solar cell according to claim 1, wherein the first isolation layer is an aluminum oxide layer or a silicon oxide layer. 3. The thin film solar cell of claim 1, wherein the second isolation layer comprises a soda-containing glass layer. 4. The thin film solar cell according to claim 1, wherein the metal substrate is a flexible substrate, and the material constituting the flexible substrate includes one or more of stainless steel, titanium and aluminum. 5. The thin film solar cell according to claim 1, wherein the back electrode layer is a molybdenum back electrode conductive layer. 6. The thin-film solar cell as claimed in claim 1, wherein the first isolation layer and the second isolation layer are manufactured to have a thickness of 1-2 micrometers and a thickness of 200-300 μm, respectively, by a radio frequency magnetron sputtering process. nanometer thickness. 7. The thin film solar cell according to claim 1, further comprising a buffer layer, a window layer, and an intrinsic zinc oxide layer between the buffer layer and the window layer, Wherein, the buffer layer is arranged between the CIGS light absorbing layer and the window layer, so as to reduce the lattice mismatch between the CIGS light absorbing layer and the window layer, and Wherein, the window layer is arranged on the intrinsic zinc oxide layer, and is used to receive the negatively charged carriers generated by the CIGS light absorbing layer, so as to prevent the Leakage. 8. A method of making a thin film solar cell, comprising: generating a first isolation layer on the metal substrate by sputtering; forming a second isolation layer on the first isolation layer by sputtering; forming a back electrode layer on the second isolation layer by sputtering; and forming a copper indium gallium selenide light absorption layer on the back electrode layer; Wherein, the first isolation layer and the second isolation layer are used to prevent metal elements in the metal substrate from entering the copper indium gallium selenide light absorption layer, and the second isolation layer includes to the CIGS light-absorbing layer to repair the sodium element of point defects caused by selenium deficiency in the CIGS light-absorbing layer. 9. The method according to claim 8, wherein the step of forming a CIGS light absorbing layer on the back electrode layer comprises forming a CIGS light absorbing layer by sputtering followed by selenization or depositing by co-evaporation A copper indium gallium selenide light absorbing layer is formed. 10. The method of claim 8, wherein the first isolation layer is an aluminum oxide layer or a silicon oxide layer, and has a thickness of 1-2 micrometers. 11. The method of claim 8, wherein the second isolation layer comprises a soda glass layer and has a thickness of 200-300 nanometers. 12. The method according to claim 8, wherein the metal substrate is a flexible substrate, and materials constituting the flexible substrate include one or more of stainless steel, titanium and aluminum. 13. The method of claim 8, further comprising: generating a buffer layer on the copper indium gallium selenide light absorbing layer by a chemical water bath method; forming an intrinsic zinc oxide layer on the buffer layer by sputtering; and A window layer is formed on the intrinsic zinc oxide layer.