CN103474483B - A kind of back reflector of periodic structure and preparation method thereof - Google Patents

Abstract

A back reflective electrode with a periodic structure, comprising a substrate layer, a first layer of metal film forming a template and a second layer of metal film for modification, the two layers of metal films are metal Ag, Al or Mo films, forming a A back reflective electrode with a periodic structure of wide-spectrum scattering; its preparation method uses a water bath method to assemble polystyrene (PS) microspheres, etches PS microspheres with _O2 plasma, and utilizes the etched polystyrene microspheres The template effect, obtain the back reflective electrode of periodic structure with broad spectrum scattering effect and be used as the back reflective electrode of thin-film solar cell. The advantages of the present invention are: utilizing the template effect of polystyrene microspheres and magnetron sputtering or evaporating metal thin films to realize the preparation of high-scattering periodic structure back reflection electrodes; when applied to thin-film solar cells, the short-circuit current density and Conversion efficiency has been improved.

Description

A kind of back reflective electrode with periodic structure and preparation method thereof

technical field

The invention belongs to the preparation technology of a high-scattering back electrode of a thin-film solar cell, in particular to a back reflection electrode with a periodic structure and a preparation method thereof.

Background technique

Photovoltaics, as the main energy source in the future, must greatly improve efficiency and reduce costs in order to survive. Silver back reflective electrode is an important part of solar cells, and its texture characteristics are very important to the performance of the cells. At present, the most widely used metal back reflector in thin film batteries is a random textured back reflector based on the metal aluminum combined with silver. The roughness of the metal back electrode grown by this method is not very large, which leads to the The scattering effect of the bottom is not very good. Studies have shown that for NIP Si-based thin-film solar cells (amorphous silicon cells, microcrystalline silicon cells, and silicon-based multi-junction thin-film laminated cells), the light trapping effect of the back reflector electrode is particularly important for device performance. The velvet metal back reflective electrode structure can effectively reflect light back to the battery and increase the optical path of light reflected back to the battery, thereby effectively enhancing the optical absorption of the intrinsic layer, increasing the short-circuit current density, and improving battery efficiency. Yes, the introduction of light trapping can reduce the thickness of the active layer of the battery, which is very important to reduce the cost.

Compared with random textured metal back reflectors, periodically structured back reflectors have attracted attention due to their high scattering properties. At present, the preparation method of the back reflector electrode with periodic structure is mainly anodized aluminum oxide (AAO). Due to the large amount of heat generated and the instability of anodic oxidation during the anodic oxidation process when the voltage is greater than 500V, its periodicity is not very good. control, and it is difficult to make a large size 'dimple' shape. Although the back reflective electrode prepared by the AAO method increases the scattering of short-wavelength light, the short-wave response of the battery is improved, and it has a light-trapping effect on short-wavelength light, but the light-trapping effect of long-wavelength light is due to its 'dimple' shape. Limited, resulting in low utilization of long-wavelength light by the battery.

Contents of the invention

The purpose of the present invention is to overcome the above-mentioned deficiencies in the prior art, and provide a back reflective electrode with a periodic structure with a high scattering ratio that is beneficial to improve the performance of thin-film solar cells. The back reflective electrode with a periodic structure can achieve good trapping Light effect, so that the unabsorbed light of the battery absorbing layer can be scattered back to the battery more, increasing the optical path of light in the battery, so as to improve the light utilization rate, enhance the short-circuit current density of the battery, and then achieve the goal of improving battery efficiency. Purpose, and the most important thing is that by controlling the preparation process, the scattering ratio in the wavelength range of 400-1500nm can be increased, so that the light utilization rate of the battery can be greatly improved.

Technical scheme of the present invention:

A back reflective electrode with a periodic structure, including a substrate layer, a first layer of metal film forming a template and a second layer of metal film for modification, the substrate layer is a hard substrate glass, and the two layers of metal film are metal Ag, Al or Mo film, wherein the thickness of the first layer of film is 300-1000nm, and the thickness of the second layer of metal film is 100-500nm, which constitutes the back reflection electrode of the periodic structure with wide spectrum scattering effect, and the back reflection electrode of the periodic structure The root mean square roughness of the reflective electrode is 50-200 nm.

A method for preparing a back reflective electrode with a periodic structure, using a water bath method to assemble polystyrene (PS) microspheres, using _O2 plasma to etch the PS microspheres, using the etched polystyrene microspheres as a template function, to obtain a back reflection electrode with a periodic structure with broad-spectrum scattering, the steps are as follows:

1) Soak the glass substrate in a mixed solution of H ₂ SO ₄ and H ₂ O ₂ with a volume ratio of 2:1 for hydrophilic treatment, and the treatment time is 2-10 hours;

2) Put the above glass substrate on a horizontal platform, drop the latex solution of polystyrene microspheres with a particle size of 1-5 μm and a concentration of 5wt% vertically on the glass substrate, and slowly spread the solution to make the vinyl microspheres Unevenly spread on the glass substrate, and then put the glass substrate on the water vapor for self-assembly. After 30 minutes of water bath, a single layer of hexagonal close-packed polystyrene microspheres are formed on the glass substrate;

3) Perform O ₂ plasma etching (RIE) on the above monolayer hexagonal close-packed polystyrene microspheres, and the size of the corresponding ethylene microspheres after etching is 0.5-4 μm;

4) Deposit the first layer of metal film with a thickness of 300-1000nm on the etched ethylene microspheres by magnetron sputtering or evaporation, and then put the glass substrate in water for ultrasonic treatment until the ethylene beads completely cleaned up;

5) A second layer of metal thin film with a thickness of 100-500nm is deposited by magnetron sputtering or evaporation to obtain a back reflection electrode with a periodic structure.

A kind of application of the back reflective electrode of described periodic structure, be used as the back reflective electrode of thin-film solar cell, described thin-film solar cell is amorphous silicon-based, microcrystalline silicon-based, nano-silicon-based thin-film solar cell, multi-junction Stacked silicon-based thin film solar cells, copper indium gallium selenide solar cells or copper zinc tin sulfur solar cells.

Advantage and positive effect of the present invention:

The present invention utilizes the template effect of polystyrene microspheres and magnetron sputtering or evaporated metal thin film to realize the preparation of the back reflective electrode of the periodic structure of high scattering; Apply the back electrode of this periodic structure to the thin film solar cell, relatively The short-circuit current density of the battery under the same conditions prepared by the traditional cashmere metal Ag film as the back reflector electrode is increased by 9.4%, the conversion efficiency is increased by 18.4%, and it has a good scattering effect on the wavelength range that can be used by the 300-1500nm battery.

Description of drawings

FIG. 1 is a schematic structural view of the back reflection electrode with the periodic structure.

Fig. 2 is a topography diagram of a back reflection electrode of an Ag thin film with a certain roughness prepared by a traditional sputtering method.

Fig. 3 is a topography diagram of a back reflection electrode with a periodic structure prepared by using PS pellets as a template.

Figure 4 shows the comparison results of integrated reflection and velvet between the back reflective electrode with periodic structure prepared by using PS balls as the template and the back reflective electrode with Ag film with certain roughness prepared by traditional sputtering method.

Figure 5 is a comparison of the external quantum efficiency of the back reflection electrode with a periodic structure prepared by using PS spheres as a template and the back reflection electrode with a certain roughness of Ag film prepared by traditional sputtering method applied to microcrystalline silicon-based solar cells result.

Figure 6 shows the cell efficiency comparison results of the back reflective electrode with a periodic structure prepared by using PS beads as a template and the back reflective electrode with a certain roughness of Ag film prepared by traditional sputtering method applied to microcrystalline silicon-based solar cells .

detailed description

Example 1:

A back reflective electrode with a periodic structure, as shown in Figure 1, includes a substrate layer, a first layer of Ag thin film forming a template effect and a second layer of Ag thin film for modification, the substrate layer is a hard substrate glass, and the two The first layer of Ag film is 600nm thick, and the thickness of the second Ag film is 300nm, forming a periodic structure back reflection electrode with wide spectrum scattering effect, and the back reflection electrode of the periodic structure The root mean square roughness of the electrode is 180nm.

A method for preparing a back reflective electrode with a periodic structure, using a water bath method to assemble polystyrene (PS) microspheres, using _O2 plasma to etch the PS microspheres, using the etched polystyrene microspheres as a template function, to obtain a back reflection electrode with a periodic structure with broad-spectrum scattering, the steps are as follows:

1) Soak the glass substrate in a mixed solution of H ₂ SO ₄ and H ₂ O ₂ with a volume ratio of 2:1 for hydrophilic treatment, and the treatment time is 5 hours;

2) Put the above glass substrate on a horizontal platform, drop the latex solution of polystyrene microspheres with a particle size of 2 μm and a concentration of 5wt% vertically on the glass substrate, and the solution slowly diffuses to make the vinyl microspheres uneven Scatter on the glass substrate, then put the glass substrate on the water vapor for self-assembly, after 30 minutes of water bath, a single layer of hexagonal close-packed polystyrene microspheres with a particle size of 2 μm are formed on the glass substrate;

3) The above-mentioned single-layer hexagonal close-packed polystyrene microspheres were subjected to _O2 plasma etching (RIE), the oxygen flow rate was 10Sccm, the air pressure was 11pa, the RF power was 150W, and the etching time was 6 minutes. The size is 1.8 μm;

4) On the etched ethylene microspheres, the first thickness of Ag film is deposited by magnetron sputtering. The target material is an Ag metal target with a purity of 99.999%. Pure argon gas sputtering is used to prepare a dense Ag film: The substrate temperature is room temperature, the background vacuum is 5×10 ^-5 Pa, the argon gas flow rate is 40 sccm, the sputtering pressure is 4 mTorr, the electrode distance is 110 mm, the sputtering power is 50 W, and the sputtering time is 28 min. Obtain the first layer of Ag film with a thickness of 600 nm, and then place the glass substrate in water for ultrasonic treatment until the vinyl beads are completely cleaned;

5) Deposit the second layer of Ag film by magnetron sputtering or evaporation. The substrate temperature is room temperature, the background vacuum is 5×10 ^-5 Pa, the argon gas flow rate is 40 sccm, the sputtering pressure is 4mTorr, and the electrode The spacing is 110 mm, the sputtering power is 50 W, and the sputtering time is 14 min, and the second layer of Ag film with a thickness of 300 nm is obtained, and the back reflective electrode with a periodic structure can be prepared.

Fig. 2 is a topography diagram of a back reflection electrode of an Ag thin film with a certain roughness prepared by a traditional sputtering method. Fig. 3 is a topography diagram of a back reflection electrode with a periodic structure prepared by using PS pellets as a template. From the comparison of the topography diagrams, it is shown that: when the back reflection electrode with a periodic structure of the present invention is used, a larger suede roughness can be obtained, and the periodic structure is obvious, and the root mean square roughness is 180nm, which is far greater than the traditional 84 nm.

Figure 4 shows the comparison results of integrated reflection and velvet between the back reflective electrode with periodic structure prepared by using PS balls as the template and the back reflective electrode with Ag film with certain roughness prepared by traditional sputtering method. The figure shows that the integral reflection and velvet of the periodic back reflection electrode are much higher than the traditional metal back reflection electrode with a certain roughness.

The prepared back reflective electrode with periodic structure was applied to microcrystalline silicon-based solar cells.

Fig. 5 is that the present invention adopts the back reflection electrode of periodic structure prepared by PS pellet as template and the back reflection electrode of the Ag film with certain roughness prepared by traditional sputtering method is applied to microcrystalline silicon-based solar cell External quantum efficiency comparison results. The figure shows that the periodic structure back reflection electrode has the effect of light trapping on the short-wave and long-wave incident light at the same time, so that the microcrystalline silicon-based solar cell has a larger short-circuit current density, and the short-circuit current density has increased by 9.4%.

Fig. 6 is the back reflective electrode of periodic structure that the present invention adopts PS ball as template preparation and the back reflective electrode of Ag thin film with certain roughness prepared by traditional sputtering method is applied to microcrystalline silicon-based solar cell Battery efficiency comparison results. The figure shows that the application of the periodic structure back reflection electrode to the microcrystalline silicon-based battery can obtain higher battery efficiency, and the conversion efficiency is increased by 18.4%.

Example 2:

A back reflection electrode with a periodic structure, as shown in Figure 1, includes a substrate layer, a first layer of Al thin film forming a template effect and a second layer of Ag thin film that acts as a modification, and the substrate layer is a hard substrate glass, wherein The thickness of the first layer of Al thin film is 500nm, and the thickness of the second layer of Ag thin film is 300nm, forming a back reflective electrode with a periodic structure with broad spectrum scattering, and the root mean square roughness of the back reflective electrode with a periodic structure is 120nm.

A method for preparing a back reflective electrode with a periodic structure, using a water bath method to assemble polystyrene (PS) microspheres, using _O2 plasma to etch the PS microspheres, using the etched polystyrene microspheres as a template function, to obtain a back reflection electrode with a periodic structure with broad-spectrum scattering, the steps are as follows:

1) Soak the glass substrate in a mixed solution of H ₂ SO ₄ and H ₂ O ₂ with a volume ratio of 2:1 for hydrophilic treatment, and the treatment time is 6 hours;

2) Put the above glass substrate on a horizontal platform, drop the latex solution of polystyrene microspheres with a particle size of 2 μm and a concentration of 5wt% vertically on the glass substrate, and the solution slowly diffuses to make the vinyl microspheres uneven Scatter on the glass substrate, then put the glass substrate on the water vapor for self-assembly, after 30 minutes of water bath, a single layer of hexagonal close-packed polystyrene microspheres with a particle size of 2 μm are formed on the glass substrate;

3) The above-mentioned single-layer hexagonal close-packed polystyrene microspheres were subjected to _O2 plasma etching (RIE), the oxygen flow rate was 10Sccm, the air pressure was 11pa, the radio frequency power was 150W, and the etching time was 9 minutes, corresponding to the ethylene microspheres The size is 1.5 μm;

4) Deposit the first thick Al film on the etched ethylene microspheres by magnetron sputtering, the target material is an Al metal target with a purity of 99.999%, and use pure argon gas sputtering to prepare a dense Al film: The substrate temperature was room temperature, the background vacuum was 5×10 ^-5 Pa, the argon gas flow rate was 40 sccm, the sputtering pressure was 4 mTorr, the electrode distance was 110 mm, the sputtering power was 50 W, and the sputtering time was 23 min. Obtain the first layer of Al film with a thickness of 500 nm, and then place the glass substrate in water for ultrasonic treatment until the ethylene pellets are completely cleaned;

5) The second layer of Ag film is deposited by magnetron sputtering or evaporation. The target material is an Ag metal target with a purity of 99.999%, and a dense Ag film is prepared by sputtering with pure argon: the substrate temperature is room temperature, and the The bottom vacuum is 5×10 ^-5 Pa, the argon gas flow rate is 40 sccm, the sputtering pressure is 4mTorr, the electrode spacing is 110 mm, the sputtering power is 50 W, and the sputtering time is 14 min, and the second layer with a thickness of 300 nm is obtained. A layer of Ag thin film can be used to produce a back reflective electrode with a periodic structure.

The technical effect of using the back reflective electrode with periodic structure of the present invention is similar to that of embodiment 1; the technical effect of applying the back reflective electrode with periodic structure to microcrystalline silicon-based solar cells is similar to that of embodiment 1.

Embodiment 3:

A back reflective electrode with a periodic structure, as shown in Figure 1, includes a substrate layer, a first layer of Ag thin film forming a template effect and a second layer of Ag thin film for modification, the substrate layer is a hard substrate glass, and the two The first layer of Ag film is 400nm thick, and the thickness of the second Ag film is 300nm, forming a periodic structure back reflection electrode with wide spectrum scattering effect, and the back reflection electrode of the periodic structure The root mean square roughness of the electrode is 85nm.

A method for preparing a back reflective electrode with a periodic structure, using a water bath method to assemble polystyrene (PS) microspheres, using _O2 plasma to etch the PS microspheres, using the etched polystyrene microspheres as a template function, to obtain a back reflection electrode with a periodic structure with broad-spectrum scattering, the steps are as follows:

1) Soak the glass substrate in a mixed solution of H ₂ SO ₄ and H ₂ O ₂ with a volume ratio of 2:1 for hydrophilic treatment, and the treatment time is 5 hours;

2) Put the above glass substrate on a horizontal platform, drop the latex solution of polystyrene microspheres with a particle size of 2 μm and a concentration of 5wt% vertically on the glass substrate, and the solution slowly diffuses to make the vinyl microspheres uneven Spread on the glass substrate, and then put the glass substrate on the water vapor for self-assembly, after 30 minutes of water bath, a single layer of hexagonal close-packed polystyrene microspheres with a particle size of 2 μm are formed on the glass substrate;

3) The above-mentioned single-layer hexagonal close-packed polystyrene microspheres were subjected to _O2 plasma etching (RIE), the oxygen flow rate was 10Sccm, the air pressure was 11pa, the RF power was 150W, and the etching time was 6 minutes. The size is 1.8 μm;

4) On the etched ethylene microspheres, the first thickness of Ag film is deposited by magnetron sputtering. The target material is an Ag metal target with a purity of 99.999%. Pure argon gas sputtering is used to prepare a dense Ag film: The substrate temperature was room temperature, the background vacuum was 5×10 ^-5 Pa, the argon flow rate was 40 sccm, the sputtering pressure was 4 mTorr, the electrode spacing was 110 mm, the sputtering power was 50 W, and the sputtering time was 19 min. Obtain the first layer of Ag film with a thickness of 400 nm, and then place the glass substrate in water for ultrasonic treatment until the vinyl beads are completely cleaned;

5) Deposit the second layer of Ag film by magnetron sputtering or evaporation. The substrate temperature is room temperature, the background vacuum is 5×10 ^-5 Pa, the argon gas flow rate is 40 sccm, the sputtering pressure is 4mTorr, and the electrode The spacing is 110 mm, the sputtering power is 50 W, and the sputtering time is 14 min to obtain a second layer of Ag film with a thickness of 300 nm, and then a back reflective electrode with a periodic structure can be prepared.

The technical effect of using the back reflective electrode with periodic structure of the present invention is similar to that of embodiment 1; the technical effect of applying the back reflective electrode with periodic structure to microcrystalline silicon-based solar cells is similar to that of embodiment 1.

Embodiment 4:

A back reflective electrode with a periodic structure, as shown in Figure 1, includes a substrate layer, a first layer of Ag thin film forming a template effect and a second layer of Ag thin film for modification, the substrate layer is a hard substrate glass, and the two The first layer of Ag film is 500nm thick, and the thickness of the second Ag film is 300nm, forming a periodic structure back reflection electrode with wide spectrum scattering effect, and the back reflection electrode of the periodic structure The root mean square roughness of the electrode is 170nm.

A method for preparing a back reflective electrode with a periodic structure, using a water bath method to assemble polystyrene (PS) microspheres, using _O2 plasma to etch the PS microspheres, using the etched polystyrene microspheres as a template function, to obtain a back reflection electrode with a periodic structure with broad-spectrum scattering, the steps are as follows:

1) Soak the glass substrate in a mixed solution of H ₂ SO ₄ and H ₂ O ₂ with a volume ratio of 2:1 for hydrophilic treatment, and the treatment time is 8 hours;

2) Put the above glass substrate on a horizontal platform, drop the latex solution of polystyrene microspheres with a particle size of 4 μm and a concentration of 5wt% vertically on the glass substrate, and the solution slowly diffuses to make the vinyl microspheres uneven Spread on the glass substrate, and then put the glass substrate on the water vapor for self-assembly, after 30 minutes of water bath, a single layer of hexagonal close-packed polystyrene microspheres with a particle size of 4 μm are formed on the glass substrate;

3) The above-mentioned single-layer hexagonal close-packed polystyrene microspheres were subjected to _O2 plasma etching (RIE), the oxygen flow rate was 10Sccm, the air pressure was 11pa, the radio frequency power was 150W, and the etching time was 15 minutes, corresponding to the ethylene microspheres The size is 3.0 μm;

4) On the etched ethylene microspheres, the first thickness of Ag film is deposited by magnetron sputtering. The target material is an Ag metal target with a purity of 99.999%. Pure argon gas sputtering is used to prepare a dense Ag film: The substrate temperature was room temperature, the background vacuum was 5×10 ^-5 Pa, the argon gas flow rate was 40 sccm, the sputtering pressure was 4 mTorr, the electrode distance was 110 mm, the sputtering power was 50 W, and the sputtering time was 23 min. Obtain the first layer of Ag film with a thickness of 500 nm, and then place the glass substrate in water for ultrasonic treatment until the vinyl beads are completely cleaned;

5) Deposit the second layer of Ag film by magnetron sputtering or evaporation. The substrate temperature is room temperature, the background vacuum is 5×10 ^-5 Pa, the argon gas flow rate is 40 sccm, the sputtering pressure is 4mTorr, and the electrode The spacing is 110 mm, the sputtering power is 50 W, and the sputtering time is 14 min to obtain a second layer of Ag film with a thickness of 300 nm, and then a back reflective electrode with a periodic structure can be prepared.

The technical effect of using the back reflective electrode with periodic structure of the present invention is similar to that of embodiment 1; the technical effect of applying the back reflective electrode with periodic structure to microcrystalline silicon-based solar cells is similar to that of embodiment 1.

Embodiment 5:

A back reflective electrode with a periodic structure, as shown in Figure 1, includes a substrate layer, a first layer of Mo metal film forming a template and a second layer of Mo metal film for modification, and the substrate layer is a hard substrate glass , the two layers of metal films are metal Mo films, wherein the thickness of the first Mo film is 600nm, and the thickness of the second Mo film is 300nm, which constitutes a periodic back reflective electrode with wide-spectrum scattering, and the periodic structure The root mean square roughness of the back reflective electrode is 160nm.

A method for preparing a back reflective electrode with a periodic structure, using a water bath method to assemble polystyrene (PS) microspheres, using _O2 plasma to etch the PS microspheres, using the etched polystyrene microspheres as a template function, to obtain a back reflection electrode with a periodic structure with broad-spectrum scattering, the steps are as follows:

1) Soak the glass substrate in a mixed solution of H ₂ SO ₄ and H ₂ O ₂ with a volume ratio of 2:1 for hydrophilic treatment, and the treatment time is 7 hours;

2) Put the above glass substrate on a horizontal platform, drop the latex solution of polystyrene microspheres with a particle size of 3 μm and a concentration of 5wt% vertically on the glass substrate, and the solution slowly diffuses to make the vinyl microspheres uneven Scatter on the glass substrate, then put the glass substrate on the water vapor for self-assembly, after 30 minutes of water bath, a single layer of hexagonal close-packed polystyrene microspheres with a particle size of 3 μm are formed on the glass substrate;

3) The above-mentioned single-layer hexagonal close-packed polystyrene microspheres were subjected to _O2 plasma etching (RIE), the oxygen flow rate was 10Sccm, the air pressure was 11pa, the radio frequency power was 150W, and the etching time was 10 minutes, corresponding to the ethylene microspheres The size is 2.4 μm;

4) On the etched ethylene microspheres, magnetron sputtering is used to deposit the first thick Mo film. The target material is a Mo metal target with a purity of 99.999%. Pure argon gas sputtering is used to prepare a dense Mo film: The substrate temperature was room temperature, the background vacuum was 5×10 ^-5 Pa, the argon flow rate was 40 sccm, the sputtering pressure was 4 mTorr, the electrode spacing was 110 mm, the sputtering power was 50 W, and the sputtering time was 24 min. Obtain the first layer of Mo film with a thickness of 600 nm, and then place the glass substrate in water for ultrasonic treatment until the ethylene pellets are completely cleaned;

5) Deposit the second layer of Mo film by magnetron sputtering or evaporation. The substrate temperature is room temperature, the background vacuum is 5×10 ^-5 Pa, the argon flow rate is 40 sccm, the sputtering pressure is 4mTorr, and the electrode The spacing is 110 mm, the sputtering power is 50 W, and the sputtering time is 15 min to obtain a second layer of Mo film with a thickness of 300 nm, and then a back reflective electrode with a periodic structure can be prepared.

The technical effect of using the back reflective electrode with periodic structure of the present invention is similar to that of embodiment 1; the technical effect of applying the back reflective electrode with periodic structure to microcrystalline silicon-based solar cells is similar to that of embodiment 1.

Embodiment 6:

A back reflection electrode with a periodic structure, as shown in Figure 1, includes a substrate layer, a first layer of Al thin film forming a template and a second layer of Al thin film for modification, the substrate layer is a hard substrate glass, and the two The first layer of Al film is 600nm thick, and the second layer of Al film is 200nm in thickness, which constitutes a periodic structure back reflection electrode with wide spectrum scattering effect, and the back reflection electrode of the periodic structure The root mean square roughness of the electrode is 140nm.

A method for preparing a back reflective electrode with a periodic structure, using a water bath method to assemble polystyrene (PS) microspheres, using _O2 plasma to etch the PS microspheres, using the etched polystyrene microspheres as a template function, to obtain a back reflection electrode with a periodic structure with broad-spectrum scattering, the steps are as follows:

1) Soak the glass substrate in a mixed solution of H ₂ SO ₄ and H ₂ O ₂ with a volume ratio of 2:1 for hydrophilic treatment, and the treatment time is 5 hours;

2) Put the above glass substrate on a horizontal platform, drop the latex solution of polystyrene microspheres with a particle size of 3 μm and a concentration of 5wt% vertically on the glass substrate, and the solution slowly diffuses to make the vinyl microspheres uneven Scatter on the glass substrate, then put the glass substrate on the water vapor for self-assembly, after 30 minutes of water bath, a single layer of hexagonal close-packed polystyrene microspheres with a particle size of 2 μm are formed on the glass substrate;

3) The above-mentioned single-layer hexagonal close-packed polystyrene microspheres were subjected to _O2 plasma etching (RIE), the oxygen flow rate was 10Sccm, the air pressure was 11pa, the radio frequency power was 150W, and the etching time was 12 minutes, corresponding to the ethylene microspheres The size is 2.2 μm;

4) Deposit the first thick Al film on the etched ethylene microspheres by magnetron sputtering, the target material is an Al metal target with a purity of 99.999%, and use pure argon gas sputtering to prepare a dense Al film: The substrate temperature is room temperature, the background vacuum is 5×10 ^-5 Pa, the argon gas flow rate is 40 sccm, the sputtering pressure is 4 mTorr, the electrode distance is 110 mm, the sputtering power is 50 W, and the sputtering time is 28 min. Obtain the first layer of Al film with a thickness of 600 nm, and then put the glass substrate in water for ultrasonic treatment until the ethylene pellets are completely cleaned;

5) Deposit the second layer of Al thin film by magnetron sputtering or evaporation. The substrate temperature is room temperature, the background vacuum is 5×10 ^-5 Pa, the argon flow rate is 40 sccm, the sputtering pressure is 4mTorr, and the electrode The spacing is 110 mm, the sputtering power is 50 W, and the sputtering time is 14 min to obtain a second layer of Al thin film with a thickness of 300 nm, and then a back reflective electrode with a periodic structure can be prepared.

The technical effect of using the back reflective electrode with periodic structure of the present invention is similar to that of embodiment 1; the technical effect of applying the back reflective electrode with periodic structure to microcrystalline silicon-based solar cells is similar to that of embodiment 1.

In summary, the present invention provides an effective method for improving the scattering characteristics of back reflective electrodes of silicon-based thin film solar cells. Microcrystalline silicon-based, nano-silicon-based thin film single-junction and multi-junction NIP solar cells. Since the back reflective electrode of the periodic structure increases the utilization of long-wavelength and short-wavelength light at the same time, it is beneficial to improve the light absorption of the battery, improve the short-circuit current of the battery, and then improve the photoelectric conversion efficiency of the solar battery.

The above is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily conceive of changes or modifications within the technical scope disclosed in the present invention. Replacement should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be determined by the protection scope of the claims.

Claims (1)

1. a preparation method of the back reflection electrode of periodic surface topography structure, described back reflection electrode comprises substrate layer, forms the first layer metal thin film of template effect and plays the second layer metal thin film of modification effect, and substrate layer is Hard substrate glass, two layers of metal films are metal Ag, Al or Mo films, the thickness of the first layer of film is 300-1000nm, and the thickness of the second layer of metal film is 100-500nm, forming a wide-spectrum scattering effect The back reflective electrode with periodic surface topography structure, the root mean square roughness of the back reflection electrode with periodic surface topography structure is 50-200nm; It is characterized in that the preparation method is: using a water bath method to assemble polystyrene microspheres, using _O2 plasma to etch the polystyrene microspheres, and using the template effect of the etched polystyrene microspheres to obtain a polystyrene microsphere with a wide spectrum. The back reflection electrode of the periodic surface topography structure of the scattering effect, the steps are as follows: 1) Soak the glass substrate in a mixed solution with a volume ratio of H ₂ SO ₄ and H ₂ O ₂ of 2:1 for hydrophilic treatment, and the treatment time is 2-10 hours; 2) Put the above-mentioned glass substrate on a horizontal platform, drop the polystyrene microsphere latex solution with a particle size of 1-5 μm and a concentration of 5wt% vertically on the glass substrate, and slowly diffuse the solution to make the polystyrene microspheres The microspheres are unevenly distributed on the glass substrate, and then the glass substrate is placed on the water vapor for self-assembly. After 30 minutes of water bath, a single layer of hexagonal close-packed polystyrene microspheres are formed on the glass substrate; 3) performing _O2 plasma etching on the single-layer hexagonal close-packed polystyrene microspheres, and the size of the polystyrene microspheres after etching is 0.5-4 μm; 4) Deposit the first metal film with a thickness of 300-1000nm on the etched polystyrene microspheres by magnetron sputtering or evaporation, and then place the glass substrate in water for ultrasonic treatment until the polystyrene Ethylene microspheres are completely cleaned; 5) A second layer of metal film with a thickness of 100-500 nm is deposited by magnetron sputtering or evaporation to obtain a back reflective electrode with a periodic surface topography.