TWI768402B - A kind of preparation method of solar cell electrode - Google Patents

Abstract

The invention discloses a method for preparing a solar cell electrode, comprising: preparing transparent conductive thin film layers on the front and back sides of a single-sided or double-sided solar cell substrate, respectively or simultaneously; and a part of the area on the transparent conductive film layer on the back side, a layer of patterned mask is prepared; the transparent conductive film layer and patterned mask on the front and back of the single-sided or double-sided solar cell are covered to prepare a non-conductive layer , and can resist acid or alkali silicon nitride, silicon or silicon oxide protective layer; remove the patterned mask on the transparent conductive film layer and the silicon nitride, silicon or silicon oxide on the patterned mask A protective layer is formed, and a metal layer conductive electrode is prepared on the exposed patterned transparent conductive film layer to complete the preparation of the solar cell electrode. By using the method to realize patterning on the ITO film of the solar cell, the process is simple and pollution-free, and the production man-hour and production cost can be effectively shortened.

Description

A kind of preparation method of solar cell electrode

The invention belongs to the field of photovoltaic cell processing, and in particular relates to a patterned manufacturing method for an ITO film on a double-sided solar cell.

At present, the front surface electrodes of crystalline silicon solar cells in the photovoltaic industry are patterned Ag grid lines formed by the technology of screen printing silver paste and sintering. However, the electrode grid line produced by this method has a small height-to-width ratio, resulting in a large shading area of the battery; residual organic substances and structural defects in the slurry after sintering lead to a large grid line resistance; silver is expensive and the sintering temperature is high (700 -800°C), which is not conducive to conversion efficiency and cost reduction.

However, as double-sided heterojunction (HIT) photovoltaic cells gradually become the leader of high-efficiency photovoltaic cells in the future, traditional silver paste printing and high-temperature sintering are no longer applicable and are satisfied with the element characteristics of heterojunction (HIT) photovoltaic cells. Tin-doped indium oxide (Indium Tin Oxide, ITO) film, as a transparent conductive film prepared from semiconductor materials, has many excellent physical properties such as high electrical conductivity, high visible light transmittance (greater than 90%), scratch resistance, etc. As well as good chemical stability and some other semiconducting properties, it is easy to prepare electrode patterns, and has been widely used in double-sided heterojunction (HIT) photovoltaic cells. In applications, ITO needs to be made into a specific pattern to act as a transparent electrode for a touch screen. The existing method is usually to sputter a thin copper film on the ITO substrate as a seed layer, and then use photo Lithography to transfer the circuit pattern. To the photoresist dry film (photo resistor), and then copper plating. After that, the photoresist is removed and copper etch back is performed to etch the previous thin copper film seed layer until the metal circuit pattern is exposed. Although the accuracy of the patterned circuit of this patterning method is high, due to the use of material photoresist, photomask and developer, the emission amount is large, and the emission will cause environmental pollution; equipment photoresist coating machine, exposure machine and developing machine are used. The cost and manufacturing cost are high, and the process steps are cumbersome, which is not conducive to mass production and reduces production costs. In addition, in the existing patterning method of the ITO film of the double-sided heterojunction (HIT) photovoltaic cell, it is easily affected by the characteristic that the ITO film will interact with the acid photosensitive material (photoresist) material, resulting in damage to the ITO film and affecting the photovoltaic effect. The electrical properties of the battery. Therefore, it is necessary to further innovate and improve the patterning method on the ITO film of the heterojunction photovoltaic cell.

In order to overcome the above shortcomings, the purpose of the present invention is to provide a preparation method for electrode metallization of double-sided solar photovoltaic cells. This method can make the process difficulty of patterning on ITO film less difficult in the future, and can effectively reduce waste. liquid discharge.

In order to achieve the above purpose, the technical solution adopted in the present invention is to provide a method for preparing a solar cell electrode, which is characterized in that it includes the following layers: on the front and back sides of a single-sided or double-sided solar cell substrate, separately or simultaneously prepare Transparent conductive thin film layer; a layer of patterned mask is prepared on partial areas of the transparent conductive thin film layer on the front and back of the single-sided or double-sided solar cell substrate; on the front and back of the single-sided or double-sided solar cell The transparent conductive thin film layer and the patterned mask are covered to prepare a non-conductive and acid or alkali resistant silicon nitride, silicon or silicon oxide protective layer; Remove the patterned mask on the transparent conductive film layer and the protective layer of silicon nitride, silicon or silicon oxide on the patterned mask, and prepare a metal layer on the exposed patterned transparent conductive film layer The conductive electrode completes the preparation of the solar cell electrode.

Through the above method, a patterned mask is formed by printing a polymer material, and after curing by thermal baking, the surface of the double-sided heterojunction solar cell is covered with silicon nitride or silicon oxide by a vacuum sputtering method. The patterned mask and the silicon nitride or silicon oxide on the patterned mask can be removed by hot water immersion bath or hot water bath/ultrasonic vibration combination to complete the patterning of the transparent conductive film layer, which is convenient for subsequent double-sided heterogeneity. Electrode metallization plating for junction photovoltaic cells. In addition, the method also utilizes the different water solubility characteristics between silicon nitride or silicon oxide and polymer materials, so that the manufacturing process of metallization of heterojunction solar photovoltaic cells not only has low cost, but also simplifies the process and reduces the discharge of waste liquid. , the advantages of shortening working hours and reducing production costs can be achieved.

FIG. 1 is a schematic diagram of the process flow of the present invention and the completed solar cell electrode.

The preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, so that the advantages and features of the present invention can be more easily understood by those skilled in the art, and the protection scope of the present invention can be more clearly defined.

Specific Example 1

Referring to Figure 1, a method for patterning an ITO film for a double-sided solar photovoltaic cell, comprising the following steps: Step 1, preparing a transparent conductive film on the front and back sides of a single-sided or double-sided solar cell substrate (step A) layer (ITO film, step B), in the double-sided heterojunction solar cell, the preparation of the transparent conductive thin film layer is the prior art, and the medium-frequency pulsed magnetron sputtering process is used to achieve; step 2, on single-sided or double-sided The upper part of the area of the transparent conductive thin film layer on the front and back of the solar cell substrate, using polymer materials to form a patterned mask by printing (step C), and the printing method includes screen printing technology or 3D printing technology; Step 3, the patterned mask formed on the transparent conductive film layer is cured by thermal baking, so that the patterned mask is shrunk to form a better aspect ratio. The thermal baking method includes an oven method. , tunnel furnace method, rapid annealing furnace and direct or indirect hot air method; Step 4, use vacuum sputtering method to cover silicon nitride, silicon or silicon oxide which is non-conductive and resistant to acid or alkali on one side or both sides respectively. A protective layer is prepared on the front side of the solar cell substrate, the transparent conductive thin film layer on the back side and the cured patterned mask (step D), which can also completely cover the four sides of the solar cell substrate at the same time; Water solubility of polymer materials, remove the patterned mask on the transparent conductive film layer and the silicon nitride, silicon or silicon oxide on the patterned mask by a hot water bath or a combination of hot water bath/ultrasonic vibration The protective layer (step E) is exposed, and the patterned transparent conductive film layer is exposed; and there is strong adhesion between the silicon nitride, silicon or silicon oxide and the transparent conductive film, and the silicon nitride, silicon or silicon oxide remains The protective layer on the transparent conductive film layer is used as the patterned mask for the subsequent metallization process.

The transparent conductive film layer on at least one side of the front or back side of the solar cell substrate should be covered at the edge (crystal edge) of the solar cell substrate to form an isolation area to avoid the transparent conductive film layer on the front and back sides of the cell on.

Use screen printing technology to form polymer material on the transparent conductive film to form the screen plate of the patterned mask, the mesh range of the screen plate is 200~500 mesh; the inner diameter of the screen is between 15~19um; the pressure under the scraper between 50~120N; the distance between the screen plate and the surface of the solar cell substrate is between 0.5mm~4mm, and the screen printing effect is good.

The polymer material of the patterned mask is a water-soluble peelable protective adhesive that is printable, soluble in water, does not chemically react with the transparent conductive film and can be cured by heating. The polymer material is convenient for subsequent peeling, and is a photovoltaic Commonly used materials in the battery industry.

In step 3, the thermal baking temperature is 100-150° C., and the thermal baking time is 10-20 minutes. The heating rate of the thermal baking method is 10 to 30°C/min. The relative reduction of the thermal energy provided during the heating process can improve the excessive growth of the thin film grains caused by the thermal energy.

In step five, the hot water bath includes a direct or indirect hot water bath method. The temperature of the hot water bath is 60~100℃, and the time of the hot water bath is 10~30 minutes.

In step 5, removing the patterned mask on the transparent conductive film layer and the protective layer of silicon nitride, silicon or silicon oxide on the patterned mask includes two methods: the first method is to remove the solar cell The base is placed in a flower basket and placed in a warm water tank for shaking or vibration; the second method is to place the solar cell substrate in a warm water tank, and install a single-point or multi-point ultrasonic vibration source in the warm water tank to vibrate multi-point ultrasonic waves. The source is 2~20.

In the vacuum sputtering method of step 4, at a temperature of 25-70° C. and a low plating rate of 1-5 nm/min, the protective layer of silicon nitride, silicon or silicon oxide is covered on the front surface of the solar cell substrate, back The transparent conductive thin film layer on the surface and the cured patterned mask, and the four sides of the solar cell substrate. The thickness of the film formed of silicon nitride, silicon or silicon oxide is 40 to 90 nm. The protective layer formed of silicon nitride or silicon oxide is effectively combined with the transparent conductive layer to form a better anti-reflection layer, which is helpful for improving the power generation efficiency of the photovoltaic cell.

The ITO film of single-sided or double-sided solar cells is patterned by the above method, only need to enter water-soluble polymer materials, screen, warm water and other materials, screen printing machine, oven, sputtering machine and other equipment, Zero pollution discharge, low cost, low cost, and simple processing steps, which can simplify the process, shorten the working hours and reduce the production cost.

In addition, when removing the patterned mask on the transparent conductive film layer and the protective layer on the patterned mask to expose the patterned transparent conductive film layer, the edges on both sides of the pattern opening must be It is a zigzag structure to increase the adhesion of the conductive electrode of the metal layer.

The zigzag R angle radius of the zigzag structure is greater than 0.05mm, which can effectively eliminate the internal stress generated during the preparation and thickening of the metal layer conductive electrode, so as to increase the adhesion of the subsequent plating metal thickening layer (step F).

Furthermore, the structure of the conductive electrode of the metal layer is an inverted convex structure or a mushroom-shaped structure. The inverted convex metal structure or the mushroom-shaped structure can effectively use the non-conductive protective layer to form a good support and increase the conductivity of the metal layer. Electrode adhesion and stability.

Specific embodiment two

After the completion of step 4 in the specific embodiment 1, the solar cell substrate covered by the protective layer of silicon nitride, silicon or silicon oxide is cured again by thermal baking. The thermal baking methods include oven method, tunnel furnace method, Rapid annealing furnace and direct or indirect hot air method, the baking temperature is 100~150℃, The hot baking time is 10~20 minutes. The patterned mask on the transparent conductive film layer is fully shrunk. The remaining steps are the same as those in the specific embodiment 1.

The above embodiments are only to illustrate the technical concept and characteristics of the present invention, and their purpose is to allow those familiar with the art to understand the content of the present invention and implement it, and cannot limit the scope of protection of the present invention. Equivalent changes or modifications made should all be included within the protection scope of the present invention.

Claims (6)

A method for preparing a solar cell electrode, comprising the steps of: preparing at least one transparent conductive film layer on the front and back sides of a single-sided or double-sided solar cell substrate, respectively or simultaneously; A layer of patterned mask is prepared on the part of the transparent conductive film layer; a layer of non-conductive, acid- or alkali-resistant silicon nitride, silicon or silicon oxide protective layer is prepared on the patterned mask; remove the transparent The patterned mask on the conductive film layer and the protective layer on the patterned mask are exposed on the patterned transparent conductive film layer to prepare a metal layer conductive electrode, that is, the preparation of the solar cell electrode is completed. The method for preparing a solar cell electrode according to claim 1, wherein the transparent conductive thin film layer on at least one side of the front side or the back side of the solar cell substrate is formed by covering the edge (crystal edge) of the solar cell substrate. The isolation area is used to avoid the conduction of the transparent conductive film layers on the front and back sides of the solar cell. The method for preparing a solar cell electrode according to claim 1, wherein the four sides of the solar cell substrate are completely covered with the protective layer of silicon nitride, silicon or silicon oxide which is non-conductive and resistant to acid or alkali . The method for preparing a solar cell electrode as claimed in claim 1, wherein the patterned transparent conductive film is exposed by removing the patterned mask on the transparent conductive film layer and the protective layer on the patterned mask. When the thin film layer is used, the edges on both sides of the pattern opening must be in a zigzag structure, so as to increase the adhesion of the conductive electrode of the metal layer. The method for preparing a solar cell electrode according to claim 4, wherein the zigzag structure has a zigzag R angle radius greater than 0.05 mm, which can effectively eliminate the internal stress generated during the preparation and thickening of the metal layer conductive electrode , to increase the adhesion of the metal thickening layer. The method for preparing a solar cell electrode according to claim 4, wherein the structure of the conductive electrode of the metal layer is an inverted convex structure or a mushroom-shaped structure, and the inverted convex structure or the mushroom-shaped structure can effectively utilize the non-conductive The protective layer forms a good support and increases the adhesion and stability of the conductive electrode of the metal layer.

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