CN106252428B - A kind of solar cell light retroreflecting is to electrode and preparation method thereof - Google Patents

Abstract

The invention relates to a photoretroreflective counter electrode of a solar cell and a preparation method thereof. The counter electrode includes a substrate, a first reflective layer, a second reflective layer, a transparent resin layer, and an adhesive layer arranged on the substrate sequentially from bottom to top And the solar cell counter electrode layer, the thickness of the second reflective layer is greater than the thickness of the first reflective layer, and the second reflective layer is evenly distributed with glass beads, and the bottom of the glass beads is embedded in the second reflective layer Among them, the upper part is embedded in a transparent resin layer; the preparation method includes substrate cleaning, coating the first reflective layer, coating the second reflective layer, embedding glass beads, coating the transparent resin layer, coating the adhesive layer and Lamination bonding and other steps. Compared with the prior art, the present invention has simple and compact overall structure, good economical practicability, low cost of materials, can effectively solve technical problems such as low light utilization rate of solar cells at present, is suitable for industrial production, and has good application prospect.

Description

Photoretroreflective counter electrode of a solar cell and preparation method thereof

technical field

The invention belongs to the technical field of solar cells, and relates to a photoretroreflective counter electrode of a solar cell and a preparation method thereof.

Background technique

A solar cell is a device that directly converts light energy into electrical energy through the photoelectric effect or photochemical effect. When sunlight irradiates on the photosensitive layer, a small part of the light is reflected by the surface, another small part of the light is absorbed by the photosensitive layer, and most of the light is transmitted. Obviously, if the transmitted light is not utilized, this part of the light will be wasted.

At present, in order to improve the efficiency of solar cells, it is a simple and effective way to place a metal film on the back of the counter electrode. By adding a layer of metal reflective film on the back of the counter electrode, the underutilized light transmitted from the photoanode is reflected back to the photoanode again, so as to achieve the purpose of secondary utilization of light. The reflection of light by the metal film will further increase the propagation path of light in the photoanode of the battery and increase its absorption of light, thereby improving the photoelectric conversion efficiency of the solar battery. However, the above method is still limited, mainly because it has the following two disadvantages: (1) the light loss of the metal reflective film is large, and the reflection efficiency cannot be very high; (2) although the metal reflective film has a high Reflectivity, but its reflection principle is specular reflection. The incident light (except vertical incident light) that reaches the surface of the metal reflective film changes after specular reflection, and the efficiency of returning to the solar cell is not high.

Contents of the invention

The object of the present invention is to provide a simple and compact structure, economical and practical, which can maximize the photoelectric conversion efficiency of solar cells, has good stability, and is suitable for industrial production of solar cells for light regression in order to overcome the defects of the above-mentioned prior art. Reflective counter electrode and preparation method thereof.

The purpose of the present invention can be achieved through the following technical solutions:

A solar cell light retroreflective counter electrode, the counter electrode includes a substrate, a first reflective layer, a second reflective layer, a transparent resin layer, an adhesive layer and a solar cell counter electrode layer arranged on the substrate in sequence from bottom to top , wherein, the thickness of the second reflective layer is greater than the thickness of the first reflective layer, and the second reflective layer is evenly distributed with glass beads, and the bottom of the glass beads is embedded in the second reflective layer , the upper part is embedded in the transparent resin layer.

Both the first reflective layer and the second reflective layer are metal reflective layers, and the thickness of the first reflective layer is ≤3 μm, and the thickness of the second reflective layer is 10-50 μm.

The glass microspheres are spherical glass microspheres with a particle diameter of 20-150 μm, and the refractive index of the spherical glass microspheres is ≥1.8.

The particle diameter of the glass microspheres is 2-3 times of the thickness of the second reflective layer.

The transparent resin layer is an acrylic resin layer or a polyvinyl butyral resin layer with a thickness of 50-100 μm.

The adhesive in the adhesive layer is a pressure-sensitive adhesive, and the thickness of the adhesive layer is 3-5 μm.

The substrate is a glass substrate, a plastic substrate or a metal substrate.

A method for preparing a light retroreflective counter electrode of a solar cell, the method specifically comprising the following steps:

(1) Substrate cleaning: take a substrate, clean the surface of the substrate with cleaning agent and water, and dry it;

(2) Coating the first reflective layer: use printing technology to evenly coat the reflective layer material on the surface of the substrate to form the first reflective layer, and make the thickness of the first reflective layer <3 μm by controlling the mesh number of the printing screen , and heated to make it fully cured;

(3) Coating the second reflective layer: Using printing technology, the reflective layer material is evenly coated on the surface of the first reflective layer to form the second reflective layer. By controlling the mesh number of the printing screen and the number of printing times, the second The thickness of the reflective layer is 10-50 μm, and it is preliminarily cured by heating;

(4) Embedding of glass microspheres: sieve to select glass microspheres of suitable particle size, adsorb on the surface of the second reflective layer, and extrude the glass microspheres adsorbed on the second reflective layer by rolling extrusion method Implanted into the second reflective layer to form a semi-embedded structure, heated to make it fully cured;

(5) Coating a transparent resin layer: dissolve the resin in a solvent, adjust the proportioning ratio of the resin and the solvent, and make the mixed solution reach a predetermined viscosity, then apply the mixed solution evenly on the surface of the second reflective layer, and wait for the solvent to After volatilization, a transparent resin layer with uniform thickness is formed;

(6) Coating the adhesive layer: uniformly coating the adhesive on the surface of the transparent resin layer and the counter electrode surface of the solar cell respectively;

(7) Lamination bonding: the surface of the counter electrode of the solar cell coated with the adhesive and the surface of the transparent resin layer are firmly bonded together by a low-pressure lamination method.

The first reflective layer material described in the step (2) is in the form of silver paste; the coating method is printing, the thickness of the reflective layer is 1-3 μm, and the heating temperature and time for the complete curing of the reflective layer depend on the substrate and the paste , if it is a glass or metal substrate and a high-temperature silver paste, the heating temperature is 400-500°C and the time is 30 minutes; if it is a plastic substrate and a low-temperature silver paste, the heating temperature is below 150°C and the time is 30 minutes.

Preferably, the plastic substrate is combined with low-temperature silver paste, and the glass substrate or metal substrate is combined with high-temperature silver paste.

The second reflective layer material described in step (3) is in the form of silver paste; the coating method is printing, the thickness of the reflective layer is 10-50 μm, and the initial solidification state of the reflective layer is that the solvent is partially volatilized, and the wet film is formed, but touch into a deformable state. The initial curing temperature and time of the reflective layer are related to the paste. If it is a low-temperature silver paste, the heating temperature should not be higher than 100°C, and the heating time should not exceed 5 minutes; if it is a high-temperature silver paste, the heating temperature should not be higher than 150°C, and the heating time should not exceed 10min. The complete curing temperature and time of the reflective layer depend on the substrate and paste. For glass substrates and high-temperature silver pastes, the heating temperature is 400-500°C for 30 minutes; for plastic substrates and low-temperature silver pastes, the heating temperature is 150°C. Below, the time is 30 minutes.

Preferably, the plastic substrate is combined with low-temperature silver paste, and the glass substrate is combined with high-temperature silver paste.

The glass beads described in the step (4) are spherical with a high refractive index, preferably glass beads with a refractive index of 2.0 or more; the particle diameter of the glass beads is greater than the thickness of the second reflective layer, and the preferred thickness is 100% of the glass beads. The particle size is 2-3 times the thickness of the second reflective layer. Since the particle size of the glass beads is larger than the thickness of the second reflective layer, a part of the glass beads is embedded in the second reflective layer, and the remaining part is exposed to the outside. In addition, since the first reflective layer has been completely cured, the glass beads The beads will not penetrate the first reflective layer. Preferably, the relationship between the glass microspheres and the reflective layer is a partially embedded relationship.

The resin described in step (5) is acrylate resin or polyvinyl butyral resin, and the solid content of resin is 10-50wt%; Described solvent comprises terpineol, ethanol, propanol, ethylene glycol, One or more of cyclohexanone, ethyl acetate or dichloromethane.

The thickness of the transparent resin layer is preferably controlled to be about 5-10 μm above the surface of the glass beads.

In step (6), the adhesive is a pressure-sensitive adhesive, preferably a self-adhesive; the adhesive layer has a thickness of 3-5 μm and is transparent. The solar cells are dye-sensitized solar cells or other types of all-solid-state solar cells, and the other types of all-solid-state solar cells are preferably perovskite solar cells. The dye-sensitized solar cells or perovskite solar cells are transparent or translucent.

The conditions of the low-pressure lamination method described in step (7) are: the control pressure is 1-2Kg/cm ² , and the time is 10-20min.

In the present invention, the glass microspheres are a new type of silicate material with a diameter of several millimeters to several microns. It not only has a high refractive index, high light transmittance and high reflectivity, but also has excellent durability Chemical corrosion and weather resistance. Due to the high refractive index of glass beads, it has unique light retroreflective properties.

What needs to be explained here is that the principle of optical retroreflection refers to the reflection of light on glass beads, and its reflection method is obviously different from diffuse reflection and specular reflection. The reflection returned by the light source, and when the incident angle of the incident light changes in a large range, it can still maintain the original direction and properties. Theoretically, this retro-reflection efficiency can reach 100%.

When the performance test of the photoretroreflective counter electrode of the solar cell prepared by the present invention is performed, the photoelectric conversion efficiency of the solar cell integrated with the photoretroreflective counter electrode is mainly placed under the illumination of AM1.5.

The light retro-reflective counter electrode of the solar cell of the present invention mainly adds a layer of light-reflective layer containing glass beads on the back of the counter electrode of the known solar cell, as a retro-reflective structure of light, and passes through the solar cell. The light that has not been fully utilized will return to the solar cell according to the original path and reflect back to the solar cell, so as to achieve the maximum secondary use of light. Theoretically, this retro-reflection efficiency can reach 100%. Therefore, the propagation path of light in the cell will be multiplied, and the source of light absorption is not only from the incident light, but also from the almost equal amount of reflected light, thereby greatly increasing its absorption of light and maximizing the photoelectricity of the solar cell. conversion efficiency. In addition, the retro-reflected light is not affected by the light intensity and angle of the incident light, so even though it is very weak and the light from different angles can also obtain an efficient reflection effect.

Compared with the prior art, the present invention has the following characteristics:

1) Glass beads have high reflection efficiency, less light loss, excellent chemical corrosion resistance and weather resistance, and long service life;

2) The paths of incident light and retro-reflected light are almost the same. The absorption of light by solar cells not only comes from incident light, but also from almost equal amounts of retro-reflected light. The absorption of light is multiplied to maximize the photoelectric conversion of solar cells. efficiency;

3) The retro-reflected light is not affected by the light intensity and angle of the incident light, although it is very weak and the light from different angles can also get an efficient reflection effect;

4) The material cost is low, and the reflective layer can be made by screen printing. The process is simple, and it is not only suitable for laboratory research, but also suitable for industrial production. It is economical and practical, has good stability, and has a good application prospect.

Description of drawings

1 is a schematic diagram of the overall structure of the light retroreflective counter electrode of the solar cell of the present invention;

Fig. 2 is the flow chart of the preparation process of the photoretroreflective counter electrode of the solar cell of the present invention;

Instructions for marks in the figure:

1—substrate, 2—first reflective layer, 3—second reflective layer, 4—glass beads, 5—transparent resin layer, 6—adhesive layer, 7—solar cell counter electrode layer, I—coating layer A reflective layer, II—coating the second reflective layer, III—embedded with glass beads, IV—coated with a transparent resin layer, V—coated with an adhesive layer, VI—laminated and combined.

detailed description

The present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments.

Example 1:

As shown in Figure 1, the light retroreflective counter electrode of the dye-sensitized solar cell in this embodiment includes a substrate 1, a first reflective layer 2, a second reflective layer 3, Transparent resin layer 5, adhesive layer 6 and solar cell counter electrode layer 7, wherein the thickness of the second reflective layer 3 is greater than the thickness of the first reflective layer 2, and the second reflective layer 3 is evenly distributed with glass beads 4 , the lower part of the glass microspheres 4 is embedded in the second reflective layer 3 , and the upper part is embedded in the transparent resin layer 5 .

As shown in Figure 2, the preparation method of the light retroreflective counter electrode of the dye-sensitized solar cell in this embodiment includes the following steps:

1) Substrate 1 cleaning

Take a stainless steel substrate 1 with a length of 2 cm and a width of 1.5 cm, and clean the surface of the substrate 1 with cleaning agent and water, and dry it.

2) Coating the first reflective layer 2

Using screen printing technology, the high-temperature silver reflective layer slurry is evenly coated on the surface of a clean stainless steel substrate 1 to form the first reflective layer 2. The mesh number of the screen is 250 mesh, and the thickness of the first reflective layer 2 is 3 microns. Heat at 400°C for 30 minutes to make it fully cured.

3) Coating the second reflective layer 3

Using screen printing technology, the high-temperature silver reflective layer paste is evenly coated on the first reflective layer 2 to form the second reflective layer 3. The screen mesh is 100 mesh, and the printing is repeated twice. The second reflective layer 3 thickness is controlled at 20 microns. Heat at 100°C for 10 minutes to make it preliminarily cured.

4) Glass beads 4 embedding

First sieve to select glass microspheres 4 of about 50 microns, and then on the surface of the second reflective layer 3, the glass microspheres 4 adsorbed on the second reflective layer 3 are extruded and implanted into the second reflective layer 3 by rolling extrusion method. A semi-buried structure is formed in the reflective layer 3 . Finally, heat at 400° C. for 30 minutes, and the partially embedded glass microspheres 4 reflective layer is completely cured.

5) Apply transparent resin layer 5

First, dissolve transparent acrylic resin into ethanol, and the weight ratio of resin and solvent is 2:8, so that the mixed solution reaches a certain viscosity, and then pour this solution on the surface of the reflective layer of glass beads 4, and coat it evenly On the surface of the reflective layer, heat at 50° C. for 30 minutes. After the solvent evaporates, a transparent film of glass beads 4 with uniform thickness is formed. The thickness of the transparent acrylic resin layer was 50 microns.

6) Coating adhesive layer 6

Apply self-adhesive on the surface of the cured transparent acrylic resin and the surface of the solar cell counter electrode layer 7 respectively. The thickness of the sticker is about 3 microns.

7) Lamination bonding

First take a known dye-sensitized solar cell, the size of which is 2 cm long and 1.5 cm wide, the counter electrode is a transparent platinum electrode, and the substrate is FTO conductive glass, and then the counter electrode of the dye-sensitized solar cell is made of The surface and the 4 light retro-reflective layers of glass beads are firmly combined together. The lamination pressure is 1Kg/cm ² , and the lamination time is 10 minutes.

8) Performance testing

Under the illumination of AM1.5, the photoelectric conversion efficiency of the dye-sensitized solar cell with light retroreflective counter electrode was tested. The results are shown in Table 1.

Example 2:

Fabrication of light retroreflective counter electrode for dye-sensitized solar cells:

1) Substrate 1 cleaning

Take a glass substrate 1 with a length of 2 cm and a width of 1.5 cm, and clean the surface of the substrate 1 with cleaning agent and water, and dry it.

2) Coating the first reflective layer 2

Using screen printing technology, the high-temperature silver reflective layer paste is evenly coated on the surface of a clean glass substrate 1 to form the first reflective layer 2. The mesh number of the screen is 250 mesh, and the thickness of the first reflective layer 2 is 2.5 microns. Heat at 500°C for 60 minutes to make it fully cured.

3) Coating the second reflective layer 3

Using screen printing technology, the high-temperature silver reflective layer paste is evenly coated on the first reflective layer 2 to form the second reflective layer 3. The screen mesh is 150 mesh, and the printing is repeated 5 times. The second reflective layer The thickness of 3 is controlled at 50 microns. Heat at 150°C for 15 minutes to make it preliminarily cured.

4) Glass beads 4 embedding

First sieve to select glass microspheres 4 of about 100 microns, and then on the surface of the second reflective layer 3, the glass microspheres 4 adsorbed on the second reflective layer 3 are extruded and implanted into the second reflective layer 3 by rolling extrusion method. A semi-buried structure is formed in the reflective layer 3 . Finally, heat at 450° C. for 60 minutes, and the partially embedded glass microspheres 4 reflective layer is completely cured.

5) Apply transparent resin layer 5

First, dissolve the transparent polyvinyl butyral resin into terpineol, the weight ratio of resin and solvent is 3:7, make the mixed solution reach a certain viscosity, and then pour this solution on the glass bead 4 reflective layer Surface, apply it evenly on the surface of the reflective layer, heat at 50°C for 10 minutes, and form a transparent film of glass beads with uniform thickness after the solvent evaporates. The transparent polyvinyl butyral resin has a thickness of 100 micrometers.

6) Coating adhesive layer 6

First take a known dye-sensitized solar cell, 2 cm long and 1.5 cm wide, the counter electrode is a transparent platinum electrode, and the substrate is FTO conductive glass, respectively on the surface of the above-mentioned cured transparent polyvinyl butyral resin and dye A self-adhesive is applied to the surface of the counter electrode of the sensitized solar cell. The thickness of the sticker is about 2 microns.

7) Lamination bonding

Then, the counter electrode surface of the dye-sensitized solar cell and the light retro-reflective layer of the glass beads 4 are firmly combined by a low-pressure lamination method. The lamination pressure is 1.5Kg/cm ² , and the lamination time is 15 minutes.

8) Performance testing

Under the illumination of AM1.5, the photoelectric conversion efficiency of the solar cell with light retroreflective counter electrode was tested. The results are shown in Table 1.

Example 3:

Fabrication of light retroreflective counter electrode for dye-sensitized solar cells:

1) Substrate 1 cleaning

Take a plastic substrate 1 with a length of 2 cm and a width of 1.5 cm, and clean the surface of the substrate 1 with cleaning agent and water, and dry it.

2) Coating the first reflective layer 2

Using screen printing technology, the low-temperature silver reflective layer paste is evenly coated on the surface of a clean glass substrate 1 to form the first reflective layer 2. The mesh number of the screen screen is 250 mesh, and the thickness of the first reflective layer 2 is 3 microns. Heat at 150°C for 30 minutes to make it fully cured.

3) Coating the second reflective layer 3

Using screen printing technology, the low-temperature silver reflective layer paste is evenly coated on the first reflective layer 2 to form the second reflective layer 3. The screen mesh is 100 mesh, and the printing is repeated 5 times. The second reflective layer The thickness of 3 is controlled at 100 microns. Heat at 50°C for 5 minutes to make it preliminarily solidified.

4) Glass beads 4 embedding

Firstly, glass microspheres 4 of about 150 microns are selected by sieving, and then on the surface of the second reflective layer 3, the glass microspheres 4 adsorbed on the second reflective layer 3 are extruded and implanted into the second reflective layer 3 by rolling extrusion method. A semi-buried structure is formed in the reflective layer 3 . Finally, heat at 150° C. for 60 minutes, and the partially embedded glass microspheres 4 reflective layer is completely cured.

5) Apply transparent resin layer 5

First, dissolve the transparent polyvinyl butyral resin into ethanol, the weight ratio of the resin and the solvent is 3:7, so that the mixed solution reaches a certain viscosity, and then pour this solution on the surface of the reflective layer of glass beads 4, Apply it evenly on the surface of the reflective layer, heat at 50°C for 20 minutes, and form a transparent film of glass beads with uniform thickness after the solvent evaporates. The transparent polyvinyl butyral resin has a thickness of 100 micrometers.

6) Coating adhesive layer 6

First take a known dye-sensitized solar cell, 2 cm long and 1.5 cm wide, the counter electrode is a transparent platinum electrode, and the substrate is FTO conductive glass, respectively on the surface of the above-mentioned cured transparent polyvinyl butyral resin and dye A self-adhesive is applied to the surface of the counter electrode of the sensitized solar cell. The thickness of the sticker is about 1 micron.

7) Lamination bonding

Then, the counter electrode surface of the dye-sensitized solar cell and the glass micro-pearl light retroreflective layer are firmly combined together by a low-pressure lamination method. The lamination pressure is 2Kg/cm ² , and the lamination time is 5 minutes.

8) Performance testing

Under the illumination of AM1.5, the photoelectric conversion efficiency of the solar cell with light retroreflective counter electrode was tested. The results are shown in Table 1.

Example 4:

Fabrication of light retroreflective counter electrode for perovskite solar cells:

1) Substrate 1 cleaning

Take a titanium substrate 1 with a length of 1.5 cm, a width of 2.5 cm and a thickness of 2 mm, and clean the surface of the substrate 1 with cleaning agent and water, and dry it.

2) Coating the first reflective layer 2

Using screen printing technology, the high-temperature silver reflective layer slurry is evenly coated on the surface of a clean titanium substrate 1 to form the first reflective layer 2. The mesh number of the screen is 250 mesh, and the thickness of the first reflective layer 2 is 2.5 microns. Heat at 500°C for 30 minutes to make it fully cured.

3) Coating the second reflective layer 3

Using screen printing technology, the high-temperature silver reflective layer paste is evenly coated on the first reflective layer 2 to form the second reflective layer 3. The screen mesh is 150 mesh, and the printing is repeated 3 times. The second reflective layer The thickness of 3 is controlled at 30 microns. Heat at 100°C for 5 minutes to make it preliminarily cured.

4) Glass beads 4 embedding

First sieve to select glass microspheres 4 of about 50 microns, and then on the surface of the second reflective layer 3, the glass microspheres 4 adsorbed on the second reflective layer 3 are extruded and implanted into the second reflective layer 3 by rolling extrusion method. A semi-buried structure is formed in the reflective layer 3 . Finally, heat at 450° C. for 30 minutes, and the partially embedded glass microspheres 4 reflective layer is completely cured.

5) Apply transparent resin layer 5

First, dissolve transparent acrylic resin into ethanol, the weight ratio of resin and solvent is 3:7, make the mixed solution reach a certain viscosity, then pour this solution on the surface of the reflective layer of glass beads 4, and spread it evenly On the surface of the reflective layer, heat at 50°C for 20 minutes, and a transparent film of glass beads with uniform thickness will be formed after the solvent evaporates. The thickness of the transparent acrylic resin layer was 100 microns.

6) Coating adhesive layer 6

Apply self-adhesive on the surface of the cured transparent acrylic resin and the surface of the solar cell counter electrode layer 7 respectively. The thickness of the sticker is about 2 microns.

7) Lamination bonding

First take a known perovskite solar cell, its size is 2.5 cm long, 1.5 cm wide, the counter electrode is a translucent gold electrode, and then the counter electrode surface of the perovskite solar cell and glass micropearl The retro-reflective layers are firmly bonded together. The lamination pressure is 1Kg/cm ² , and the lamination time is 5 minutes.

8) Performance testing

Under the illumination of AM1.5, the photoelectric conversion efficiency of the perovskite solar cell with light retroreflective counter electrode was tested. The results are shown in Table 1.

Table 1 Solar Cell Efficiency

Example 5:

The light retroreflective counter electrode of the solar cell in this embodiment includes a substrate 1, a first reflective layer 2, a second reflective layer 3, a transparent resin layer 5, an adhesive layer 6, and a solar cell arranged sequentially on the substrate 1 from bottom to top. Counter electrode layer 7, wherein the thickness of the second reflective layer 3 is greater than the thickness of the first reflective layer 2, and the second reflective layer 3 is evenly distributed with glass beads 4, and the bottom of the glass beads 4 is embedded in the second In the reflective layer 3 , the upper part is embedded in the transparent resin layer 5 .

Wherein, both the first reflective layer 2 and the second reflective layer 3 are metal reflective layers, and the thickness of the first reflective layer 2 is 1 μm, and the thickness of the second reflective layer 3 is 10 μm.

The glass microspheres 4 are spherical glass microspheres 4 with a particle diameter of 20 μm, and the refractive index of the spherical glass microspheres 4 is ≥1.8.

The transparent resin layer 5 is an acrylic resin layer with a thickness of 50 μm. The adhesive in the adhesive layer 6 is a pressure-sensitive adhesive, and the thickness of the adhesive layer 6 is 3 μm. The substrate 1 is a glass substrate.

The preparation method of the light retroreflective counter electrode of the solar cell in this embodiment specifically includes the following steps:

(1) Cleaning of the substrate 1: take a substrate 1, clean the surface of the substrate 1 with cleaning agent and water, and dry it;

(2) Coating the first reflective layer 2: Using printing technology, the reflective layer material is evenly coated on the surface of the substrate 1 to form the first reflective layer 2. By controlling the mesh number of the printing screen, the first reflective layer 2 The thickness is 1μm, and it is fully cured by heating;

(3) Coating the second reflective layer 3: using printing technology, the reflective layer material is uniformly coated on the surface of the first reflective layer 2 to form the second reflective layer 3, by controlling the mesh number of the printing screen and the number of times of printing, Make the thickness of the second reflective layer 3 be 10 μm, and heat to make it preliminarily solidified;

(4) Embedding of glass microspheres 4: glass microspheres 4 of suitable particle size are selected by sieving, adsorbed on the surface of the second reflective layer 3, and the glass beads adsorbed on the second reflective layer 3 are absorbed by the rolling extrusion method. Microbeads 4 are extruded and implanted into the second reflective layer 3 to form a semi-embedded structure, and heated to make them completely solidified;

(5) Coating the transparent resin layer 5: dissolving the resin in the solvent, adjusting the proportioning ratio of the resin and the solvent, so that the mixed solution reaches a predetermined viscosity, and then the mixed solution is evenly coated on the surface of the second reflective layer 3, After the solvent evaporates, a transparent resin layer 5 with uniform thickness is formed;

(6) Coating the adhesive layer 6: uniformly coating the adhesive on the surface of the transparent resin layer 5 and the surface of the counter electrode of the solar cell respectively;

(7) Lamination bonding: the surface of the counter electrode of the solar cell coated with the adhesive and the surface of the transparent resin layer 5 are firmly bonded together by a low-pressure lamination method.

The resin in step (5) is an acrylate resin with a solid content of 10 wt %; the solvent is formed by mixing terpineol, ethanol, cyclohexanone and ethyl acetate in a volume ratio of 2:1:2:1.

The conditions of the low-pressure lamination method in step (7) are: the control pressure is 1Kg/cm ² , and the time is 20 minutes.

Embodiment 6:

The light retroreflective counter electrode of the solar cell in this embodiment includes a substrate 1, a first reflective layer 2, a second reflective layer 3, a transparent resin layer 5, an adhesive layer 6, and a solar cell arranged sequentially on the substrate 1 from bottom to top. Counter electrode layer 7, wherein the thickness of the second reflective layer 3 is greater than the thickness of the first reflective layer 2, and the second reflective layer 3 is evenly distributed with glass beads 4, and the bottom of the glass beads 4 is embedded in the second In the reflective layer 3 , the upper part is embedded in the transparent resin layer 5 .

Wherein, both the first reflective layer 2 and the second reflective layer 3 are metal reflective layers, and the thickness of the first reflective layer 2 is 1.5 μm, and the thickness of the second reflective layer 3 is 30 μm.

The glass microspheres 4 are spherical glass microspheres 4 with a particle diameter of 75 μm, and the refractive index of the spherical glass microspheres 4 is ≥1.8.

The transparent resin layer 5 is a polyvinyl butyral resin layer with a thickness of 100 μm. The adhesive in the adhesive layer 6 is a pressure-sensitive adhesive, and the thickness of the adhesive layer 6 is 5 μm. The substrate 1 is a plastic substrate.

The preparation method of the light retroreflective counter electrode of the solar cell in this embodiment specifically includes the following steps:

(1) Cleaning of the substrate 1: take a substrate 1, clean the surface of the substrate 1 with cleaning agent and water, and dry it;

(2) Coating the first reflective layer 2: Using printing technology, the reflective layer material is evenly coated on the surface of the substrate 1 to form the first reflective layer 2. By controlling the mesh number of the printing screen, the first reflective layer 2 The thickness is 1.5μm, and it is fully cured by heating;

(3) Coating the second reflective layer 3: using printing technology, the reflective layer material is uniformly coated on the surface of the first reflective layer 2 to form the second reflective layer 3, by controlling the mesh number of the printing screen and the number of times of printing, Make the thickness of the second reflective layer 3 be 30 μm, and heat it to make it preliminarily solidify;

(4) Embedding of glass microspheres 4: glass microspheres 4 of suitable particle size are selected by sieving, adsorbed on the surface of the second reflective layer 3, and the glass beads adsorbed on the second reflective layer 3 are absorbed by the rolling extrusion method. Microbeads 4 are extruded and implanted into the second reflective layer 3 to form a semi-embedded structure, and heated to make them completely solidified;

(5) Coating the transparent resin layer 5: dissolving the resin in the solvent, adjusting the proportioning ratio of the resin and the solvent, so that the mixed solution reaches a predetermined viscosity, and then the mixed solution is evenly coated on the surface of the second reflective layer 3, After the solvent evaporates, a transparent resin layer 5 with uniform thickness is formed;

(6) Coating the adhesive layer 6: uniformly coating the adhesive on the surface of the transparent resin layer 5 and the surface of the counter electrode of the solar cell respectively;

(7) Lamination bonding: the surface of the counter electrode of the solar cell coated with the adhesive and the surface of the transparent resin layer 5 are firmly bonded together by a low-pressure lamination method.

In step (5), the resin is polyvinyl butyral resin with a solid content of 50 wt %; the solvent is formed by mixing terpineol, ethylene glycol and methylene chloride in a volume ratio of 2:1:1.

The conditions of the low-pressure lamination method in step (7) are: the control pressure is 2Kg/cm ² , and the time is 10 minutes.

The above descriptions of the embodiments are for those of ordinary skill in the art to understand and use the invention. It is obvious that those skilled in the art can easily make various modifications to these embodiments, and apply the general principles described here to other embodiments without creative effort. Therefore, the present invention is not limited to the above-mentioned embodiments. Improvements and modifications made by those skilled in the art according to the disclosure of the present invention without departing from the scope of the present invention should fall within the protection scope of the present invention.

Claims (10)

1. A solar cell light retroreflective counter electrode, characterized in that the counter electrode comprises a substrate, a first reflective layer, a second reflective layer, a transparent resin layer, and an adhesive layer that are arranged on the substrate sequentially from bottom to top And the solar cell counter electrode layer, wherein, the thickness of the second reflective layer is greater than the thickness of the first reflective layer, and the second reflective layer is evenly distributed with glass beads, and the lower part of the glass beads is embedded In the second reflective layer, the upper part is embedded in a transparent resin layer. 2. A solar cell light retroreflective counter electrode according to claim 1, characterized in that, both the first reflective layer and the second reflective layer are metal reflective layers, and the first reflective layer of the Thickness≤3μm, the thickness of the second reflective layer is 10-50μm. 3. a kind of solar cell light retroreflection counter electrode according to claim 1, is characterized in that, described glass microsphere is the spherical glass microsphere that particle diameter is 20-150 μ m, and the refractive index of this spherical glass microsphere ≥1.8. 4 . The light retroreflective counter electrode of a solar cell according to claim 3 , wherein the particle diameter of the glass microspheres is 2-3 times the thickness of the second reflective layer. 5 . The photoretroreflective counter electrode of a solar cell according to claim 1 , wherein the transparent resin layer is an acrylic resin layer or a polyvinyl butyral resin layer with a thickness of 50-100 μm. 6. A solar cell light retroreflective counter electrode according to claim 1, wherein the adhesive in the adhesive layer is a pressure-sensitive adhesive, and the adhesive The thickness of the layer is 3-5 μm. 7 . The photoretroreflective counter electrode of a solar cell according to claim 1 , wherein the substrate is a glass substrate, a plastic substrate or a metal substrate. 8. A method for preparing a solar cell light retroreflective counter electrode as claimed in any one of claims 1 to 7, characterized in that the method specifically comprises the following steps: (1) Substrate cleaning: take a substrate, clean the surface of the substrate with cleaning agent and water, and dry it; (2) Coating the first reflective layer: use printing technology to evenly coat the reflective layer material on the surface of the substrate to form the first reflective layer, and make the thickness of the first reflective layer <3 μm by controlling the mesh number of the printing screen , and heated to make it fully cured; (3) Coating the second reflective layer: Using printing technology, the reflective layer material is evenly coated on the surface of the first reflective layer to form the second reflective layer. By controlling the mesh number of the printing screen and the number of printing times, the second The thickness of the reflective layer is 10-50 μm, and it is preliminarily cured by heating; (4) Embedding of glass microspheres: sieve to select glass microspheres of suitable particle size, adsorb on the surface of the second reflective layer, and extrude the glass microspheres adsorbed on the second reflective layer by rolling extrusion method Implanted into the second reflective layer to form a semi-embedded structure, heated to make it fully cured; (5) Coating a transparent resin layer: dissolve the resin in a solvent, adjust the ratio of the resin and the solvent, and then evenly coat the mixed solution on the surface of the second reflective layer. After the solvent volatilizes, a transparent layer with uniform thickness is formed. resin layer; (6) Coating the adhesive layer: uniformly coating the adhesive on the surface of the transparent resin layer and the counter electrode surface of the solar cell respectively; (7) Lamination bonding: the surface of the counter electrode of the solar cell coated with the adhesive and the surface of the transparent resin layer are firmly bonded together by a low-pressure lamination method; The glass microspheres are spherical glass microspheres with a particle diameter of 20-150 μm. 9. the preparation method of a kind of solar cell light retroreflection counter electrode according to claim 8 is characterized in that, the resin described in step (5) is acrylic ester resin or polyvinyl butyral resin, and the resin The solid content is 10-50 wt%. The solvent includes one or more of terpineol, ethanol, propanol, ethylene glycol, cyclohexanone, ethyl acetate or methylene chloride. 10. the preparation method of a kind of solar cell light retroreflection counter electrode according to claim 8, is characterized in that, the condition of the low pressure lamination method described in step (7) is: control pressure is 1-2Kg/cm ² , the time is 10-20min.