KR101396445B1 - Method of preparing front electrode of solar cell and method of preparing solar cell using the same - Google Patents

Abstract

The present invention relates to a method for manufacturing a front electrode of a solar cell and a method for manufacturing a solar cell and, more specifically, to a method for manufacturing a front electrode of a solar cell using an etching paste to form an opening part at an anti-reflective layer, and forming an electrode at the area corresponding to the opening part. A high-efficiency solar cell can be manufactured by optimizing each process condition of the method for manufacturing a front electrode of the solar cell.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a method of manufacturing a front electrode of a solar cell, and a method of manufacturing a solar cell using the same. BACKGROUND ART [0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a method of manufacturing a front electrode of a solar cell and a method of manufacturing a solar cell using the same, and more particularly to a method of manufacturing a front electrode of a solar cell using a non-contact metallization A method of manufacturing a front electrode of a battery, and a method of manufacturing a solar cell using the method.

Recently, as existing energy resources such as oil and coal are expected to be depleted, interest in alternative energy that can replace them is increasing. Among them, solar cells are attracting attention as next-generation batteries using semiconductor devices that convert solar energy directly into electric energy.

Solar cells are divided into silicon solar cell, compound semiconductor solar cell and tandem solar cell. Among them, silicon solar cells are mainstream.

Such a solar cell generally includes a semiconductor substrate and a semiconductor emitter layer made of semiconductors having different conductive types such as a p-type and an n-type, a reflective layer formed on a semiconductor emitter layer, An antistatic layer, a conductive electrode layer formed on the antireflection layer, a front electrode formed on the conductive electrode layer, and a rear electrode formed on the semiconductor substrate. Therefore, a p-n junction is formed at the interface between the semiconductor substrate and the semiconductor emitter layer.

In the production of conventional silicon solar cells, in addition to the cost ratio of wafers, the electrode materials consumed for forming the conductive pattern also account for the high cost portion, and it is necessary to increase cost competitiveness by reducing material cost. Conventionally, a screen printing method in which a pressure is applied has been used in the process of forming an electrode of a crystalline silicon solar cell. However, an increase in the breakage rate due to the thinning of the crystalline silicon wafer is a problem.

The inkjet printing method is a technology maximizing utilization of materials compared with other existing technologies and is a digital printing method which does not require consumable parts such as screen plate. Accordingly, not only can the consumed amount of the electrode material composed of the expensive silver be significantly reduced, but also the cost of consuming the screen plate and the like can be reduced. However, in the inkjet printing method, it is impossible to eject ink having a size larger than that of the nozzle size. When ink having a high viscosity is applied, there is a risk that the nozzle sticks to the side surface of the discharge nozzle to clog the nozzle.

Also, the conductive transparent electrode layer on the front electrode of the silicon solar cell is formed through an interfacial reaction between the metal paste and the antireflection layer. At this time, the silver contained in the metal paste becomes a liquid at a high temperature and then recrystallized into a solid phase, And contact with the emitter layer through a punch through phenomenon through the antireflection layer via a glass frit. The glass frit powder causes an interfacial reaction with the antireflective film to etch the antireflective layer, which is an oxidation-reduction reaction in which some elements are reduced to form byproducts. Therefore, the conventional process of performing the screen printing with the silver-containing paste includes the glass frit for forming the antireflection film when the front electrode is formed. However, since the glass frit is contained, it has a bad influence on the electric conductivity and the dispersion stability of the metal paste is poor.

Therefore, in manufacturing the front electrode of the solar cell, it is necessary to increase the contact of the emitter layer with the conductive transparent electrode layer, and to solve problems such as the electric conductivity of the solar cell and the dispersion stability of the metal paste for forming the conductive layer It is necessary to develop a manufacturing method.

In order to solve the problems of the prior art as described above, the present invention eliminates the need to apply pressure to the silicon substrate at the time of forming the electrodes, minimizes physical damage to the substrate, reduces the amount of wasted material, A method of manufacturing a solar cell front electrode in which the contact force between the emitter layer and the conductive electrode layer is increased, and a manufacturing method of the solar cell including the same.

It is another object of the present invention to provide an optimum condition for producing a solar cell with high efficiency in each step of the method for manufacturing the solar cell front electrode.

In order to accomplish the above object, the present invention provides a method of manufacturing a semiconductor device, comprising: forming an emitter layer on a substrate; Forming an anti-reflective layer on the emitter layer; Applying an etching paste to a part of the surface of the antireflection layer, and then removing the part of the antireflection layer to form an opening; Printing a first composition for forming a conductive layer on the opening of the antireflection layer by non-contact metallization to form a first conductive layer; Printing a second composition for forming a conductive layer on the first conductive layer to form a second conductive layer; And firing the first conductive layer and the second conductive layer.

The present invention also provides a method of manufacturing a semiconductor device, comprising: forming an emitter layer on a substrate; Forming an anti-reflective layer on the emitter layer; Applying an etching paste to a part of the surface of the antireflection layer, and then removing the part of the antireflection layer to form an opening; Printing a first composition for forming a conductive layer on the opening of the antireflection layer by non-contact metallization to form a first conductive layer; Printing a second composition for forming a conductive layer on the first conductive layer to form a second conductive layer; Applying a composition for forming a rear electrode to a back surface of the substrate; And a step of firing the solar cell.

According to the manufacturing method of the solar cell front electrode and the manufacturing method of the solar cell according to the present invention, there is no need to form the electrode by applying pressure to the silicon substrate, so that the physical damage to the substrate can be minimized, It is possible to manufacture a solar cell having an increased contact force between the emitter layer and the conductive electrode layer.

In addition, the solar cell manufactured according to the method of the present invention has a sheet resistance of about 60 to 120 OMEGA / sq, and the sheet resistance of the emitter layer of the conventional crystalline solar cell is about 40 to 50 OMEGA / sq. Therefore, the photoelectric conversion efficiency is excellent. In other words, the portion of the emitter layer formed on the entire surface of the solar cell layer where the dead layer (the region where the generated electrons are hindered by the extra semiconductor impurity concentration) is formed is smaller, which is more efficient than the conventional solar cell , Effectively converting solar energy directly into electrical energy.

FIG. 1 schematically shows a cross-sectional structure of a solar cell according to an embodiment of the present invention.
2 is a schematic diagram of a solar cell manufacturing process according to an embodiment of the present invention.

A method of manufacturing a front electrode of a solar cell according to the present invention includes: forming an emitter layer on a substrate; Forming an anti-reflective layer on the emitter layer; Applying an etching paste to a part of the surface of the antireflection layer, and then removing the part of the antireflection layer to form an opening; Printing a first composition for forming a conductive layer on the opening of the antireflection layer by non-contact metallization to form a first conductive layer; Printing a second composition for forming a conductive layer on the first conductive layer to form a second conductive layer; And firing the first and second conductive layers.

In the present invention, the terms first, second, etc. are used to describe various components, and the terms are used only for the purpose of distinguishing one component from another.

Moreover, the terminology used herein is for the purpose of describing exemplary embodiments only and is not intended to be limiting of the present invention. The singular expressions include plural expressions unless the context clearly dictates otherwise. In this specification, the terms "comprising," "comprising," or "having ", and the like are intended to specify the presence of stated features, But do not preclude the presence or addition of one or more other features, integers, steps, components, or combinations thereof.

Also in the present invention, when referring to each layer or element being "on" or "on" each layer or element, it is meant that each layer or element is formed directly on each layer or element, Layer or element may be additionally formed between each layer, the object, and the substrate.

While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that the invention is not intended to be limited to the particular forms disclosed, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.

Hereinafter, a method of manufacturing a solar cell front electrode and a solar cell manufacturing method of the present invention will be described in detail.

A method of manufacturing a solar cell front electrode according to an aspect of the present invention includes: forming an emitter layer on a substrate; Forming an anti-reflective layer on the emitter layer; Applying an etching paste to a part of the surface of the antireflection layer, and then removing the part of the antireflection layer to form an opening; Printing a first composition for forming a conductive layer on the opening of the antireflection layer by non-contact metallization to form a first conductive layer; Printing a second composition for forming a conductive layer on the first conductive layer to form a second conductive layer; And firing the first and second conductive layers.

In the present specification, the substrate means a silicon semiconductor substrate.

According to one embodiment of the present invention, the substrate is a silicon semiconductor substrate, which may be doped with a P-type impurity, and the emitter layer may be doped with an N-type impurity. For example, the substrate may be doped with an impurity such as boron (B), gallium (Ga), indium (In) or the like which is a group III element and the emitter layer may be doped with phosphorus ), Antimony (Sb), or the like can be doped with an impurity. When the substrate and the emitter layer are doped with an impurity of the opposite conductivity type, a P-N junction is formed at the interface between the substrate and the emitter layer.

According to one embodiment of the invention, the anti-reflection layer is silicon nitride, silicon nitride, silicon oxide containing hydrogen, magnesium fluoride (MgF _2), zinc sulfide (ZnS), titanium oxide (TiO _2), cerium oxide (CeO ₂ ), And a mixture thereof. [0033] The term " single-layer or multi-layer film " The anti-reflective layer immobilizes defects present in the surface or bulk of the emitter layer and reduces the reflectivity of sunlight incident on the front surface of the substrate. When defects present in the emitter layer are passivated, the recombination sites of the minority carriers are removed and the open-circuit voltage (Voc) of the solar cell increases. When the reflectance of sunlight is reduced, the total amount of light reaching the PN junction is increased and the short circuit current Isc of the solar cell is increased. As the open-circuit voltage and the short-circuit current of the solar cell are increased by the antireflection layer, the conversion efficiency of the solar cell is improved accordingly.

The step of forming an emitter layer on the substrate and the step of forming an anti-reflective layer on the emitter layer may be performed by a conventional solar cell manufacturing process.

The method of manufacturing a solar cell front electrode of the present invention includes the step of applying an etching paste to a partial area of the antireflection layer and then removing the partial area of the antireflection layer to form an opening.

According to an embodiment of the present invention, the etching paste is for forming an opening for exposing the emitter layer to the outside by eroding the antireflection layer, and the etching paste is applied to a desired area on the antireflection layer, The antireflection layer can be removed.

The method of applying the etching paste is not particularly limited and may be printed by a non-contact printing method such as electrohydrodynamic printing (EHD) or a screen printing method. According to an embodiment of the present invention, The anti-reflection layer may be removed by printing the etching paste using an electrohydrodynamic printing (EHD) method to form an opening. At this time, the anti-reflection layer is removed in a groove having a predetermined width An opening may be formed to expose the emitter layer. For example, the shape of the opening may be electrode-shaped and may be removed with a line width of about 40 to about 80 micrometers. The first conductive layer and the second conductive layer may be formed on the emitter layer of the opening region in which the antireflection layer is removed. According to an embodiment of the present invention, the method of removing the anti-reflection layer may be a method using ultrasonic processing. For example, after the application of the etching paste, the anti-reflection layer separated by the etching paste can be removed by ultrasonic treatment in a water bath containing the KOH solution, but not limited thereto.

According to an embodiment of the present invention, the region of the first conductive layer may be formed on the emitter layer to correspond to the opening region of the anti-reflection layer, and the region of the second conductive layer may be formed on the emitter layer, Region of the first conductive layer.

Since the first conductive layer is formed by non-contact metallization in the opening region of the antireflection layer, the first conductive layer comes into direct contact with the emitter layer without a separate layer in between. At this time, since the silicide compound is formed at the interface between the first conductive layer and the emitter layer, thereby reducing the surface resistance of the electrode, the region of the first conductive layer is formed to correspond to the opening region as described above And the second conductive layer may be formed so as to correspond to the first conductive layer region or further include a margin of the opening line width including the first conductive layer region.

According to an embodiment of the present invention, the method may further include drying the etching paste before the step of removing the anti-reflection layer after printing the etching paste, and the drying may be performed at a temperature of about 250 to about 350 Deg.] C, preferably about 300 to about 350 [deg.] C, and more preferably about 320 to about 340 [deg.] C. In the drying step, the reaction progress of the etching paste and the antireflection layer may vary depending on the drying temperature. When the antireflection layer is dried at a temperature lower than about 250 ° C, the antireflection layer may not be completely removed due to weak reaction. The contact between the electrode and the emitter layer is poor and the efficiency of the manufactured solar cell may be lowered. If the substrate is dried at a temperature exceeding about 350 ° C, the etching paste and the antireflection layer may be excessively reacted to damage the emitter layer And the efficiency of the produced solar cell may be lowered.

The first composition for forming the first conductive layer may include conductive metal particles, a solvent, a binder and a dispersing agent. In addition, components and contents commonly used in this technical field may be applied to the present invention. have.

According to an embodiment of the present invention, the first composition may include at least one selected from the group consisting of nickel (Ni), titanium (Ti), cobalt (Co), platinum (Pt), palladium (Pd), molybdenum (Cu), tungsten (W), and alloys thereof may be contained as the conductive metal particles, and preferably, it may include nickel (Ni). However, And is not particularly limited as long as it is a conductive metal particle capable of forming a silicide compound with the emitter layer. When the emitter layer and the silicide compound are formed, the electrode surface resistance can be reduced as described above, and the efficiency of the solar cell can be increased.

According to one embodiment of the present invention, the first composition may comprise about 15 to about 35 wt% of the nickel (Ni) relative to the total weight of the first composition. When the first composition contains less than about 15% by weight of nickel (Ni), the efficiency of the second photoconductive layer may be reduced due to insufficient contact between the second conductive layer and the emitter layer, , The content of nickel (Ni) having an electric conductivity which is worse than that of silver (Ag) of the second conductive layer in the electrode of the manufactured solar cell is increased, The efficiency of the solar cell may be lowered.

The binder usable in the first composition of the present invention is used for bonding the respective components before firing the electrodes. It is preferable that the binder is produced by suspension polymerization for uniformity of each component in the first composition. As such a binder, the polymer surface soluble in the solvent can be used without any limitation, and specifically, a resin containing a carboxyl group, a carboxyl group-containing photosensitive resin having an ethylenically unsaturated double bond per se, and an ethylenically unsaturated double And a carboxyl group-containing resin having no bond. For example, a carboxyl group-containing photosensitive resin obtained by copolymerizing an unsaturated carboxylic acid and a compound having an unsaturated double bond and a copolymer of a carboxyl group-containing photosensitive resin and a compound having an unsaturated carboxylic acid and an unsaturated double bond as a pendant, Resin, a carboxyl group-containing photosensitive resin obtained by reacting a copolymer of an acid anhydride having an unsaturated double bond and a compound having an unsaturated double bond with a compound having a hydroxyl group and an unsaturated double bond, and a mixture thereof, But are not limited to, alkylphenol-formaldehyde copolymers, polyvinylpyrrolidone (PVP), polyvinyl alcohol (PVA), ethyl cellulose, and the like.

The binder is preferably contained in an amount of about 0.1 to 5 wt% based on the total weight of the first composition. When the content of the binder is less than about 0.5 wt%, the distribution of the binder in the electrode pattern to be formed may be uneven, Patterning due to selective exposure and development may be difficult. When the amount exceeds about 5% by weight, pattern collapse may easily occur during firing of the electrode, and the resistance of the electrode may increase due to the organic residue after firing (Carbon ash) .

The dispersant may be a copolymer having an acid value of about 50 mg KOH / g or more and an amine value of about 100 mg KOH / g or less as a component to help each component to be uniformly distributed in the first composition . For example, BYK 102 (acid value: 101 mg KOH / g, amine value: 0 mg KOH / g), BYK 110 (acid value: 53 mg KOH / g, amine value: 0 mg KOH / g), BYK 102 BYK 995 (acid value: 53 mg KOH / g, amine value: 0 mg KOH / g), BYK 145 (acid value: 76 mg KOH / g, , BYK 996 (acid value: 71 mg KOH / g, and amine value: 0 mg KOH / g) can be used as a dispersant. The dispersing agent may be included in an amount of about 0.5 to 5% by weight based on the total weight of the first composition.

According to an embodiment of the present invention, the solvent may dissolve the binder and may be mixed well with other additives, and a low boiling point solvent and a high boiling point solvent may be mixed.

The low boiling point solvent as the main solvent may be a low boiling point glycol ether having a hydroxyl group at the terminal group and a boiling point of about 130 to 210 캜, preferably about 170 to 210 캜. If the boiling point of the low boiling point solvent is less than about 130 ° C, the jetting property may deteriorate. If the boiling point of the low boiling point solvent is more than about 210 ° C, the drying speed is low after jetting.

The low boiling point solvent is preferably contained in an amount of about 30 to 70% by weight based on the total weight of the first composition. When the content of the solvent is less than about 30% by weight, the composition may be difficult to uniformly coat. When the content of the solvent is more than about 70% by weight, sufficient conductivity may not be exhibited in the electrode pattern formed.

Preferred low boiling solvents are, for example, diethylene glycol monomethyl ether (DMG), diethylene glycol monoethyl ether (ethyl carbitol), diethylene glycol monobutyl ether (Diethylene glycol monoethyl ether) Diethylene glycol monoalkyl ethers such as Glycol monobutyl ether (butyl carbitol); Or ethylene glycol ethyl ether (ethyl cellosolve), ethylene glycol propyl ether (propyl cellosolve), ethylene glycol n-butyl ether (n-butyl cellosolve) Ethylene glycol monoalkyl ethers such as ethylene glycol monoalkyl ethers such as ethylene glycol monoalkyl ethers such as ethylene glycol monoalkyl ether.

The high boiling solvent is a solvent having a hydroxyl group at the terminal group and a boiling point of from about 240 to about 300 캜, preferably from about 240 to about 270 캜, for example, diethylene glycol, glycerol ), Tripropyleneglycolmethylether, but are not limited thereto.

The content of the high boiling point solvent may be about 3 to about 10 wt% based on the total weight of the first composition, and if the content is less than about 3 wt%, the jetting property may deteriorate, , The drying speed after the jetting is slow, and the spreading phenomenon may be increased.

The first composition for forming an electrode according to an embodiment of the present invention may further contain additives such as a thickener, a thixotropic agent and a leveling agent. The amount of the additive may be in the range of About 1 to about 20 parts by weight.

In the preparation of the first composition, the steps of stirring and pulverizing may be performed by ball milling or the like, and the particles may be agglomerated or removed from the particle diameter range through filtration. But it is not limited thereto, and can be produced through a process such as flame spray pyrolysis or plasma treatment.

According to an embodiment of the present invention, in the step of forming the first conductive layer by printing the first composition by non-contact metallization, the printing method may be an electrohydrodynamic printing (EHD) . Electrohydrodynamics printing (EHD) is a printing method in which droplets are ejected using an electric field. When a constant voltage is applied between the ejection nozzle and the substrate, an electric field is generated. At the same time, . In this case, when the pressure of the nozzle is larger than the surface tension of the fluid due to the electric charge and the electric field generated on the surface of the fluid, the spherical surface deforms into the shape of Taylor Cone, resulting in a much smaller particle size or spray than the size of the nozzle. The formation of Taylor Cone by an electric field can generate an actual droplet or a single droplet of a size of several hundred nm to several μm from a large nozzle having a relatively large size of several tens of μm to a few hundreds of μm, thereby improving the line width resolution and reducing the frequency of clogging Advantages can be realized at the same time, and the electric field can be optimized to improve the straightness of discharged droplets.

In addition, electrohydrodynamics printing (EHD) can minimize physical damage to the substrate by eliminating the need to form an electrode by applying pressure to the silicon substrate, such as screen printing, and the amount of wasted material is small. The electrode can be formed utilizing the electrode material of a wide viscosity range without being greatly affected by the viscosity of the material. Particularly, in the case of a first conductive layer containing nickel (Ni) to which a thin layer electrode is to be applied, silver (Ag), which forms a thin layer by printing using low viscosity ink and has a high aspect ratio In the case of the second conductive layer including the electrode, the electrode can be formed utilizing the high viscosity ink. This solves the limitations of inkjet and screen printing. Therefore, when electrohydrodynamic printing (EHD) is used for forming the first conductive layer, it is possible to accurately form the first conductive layer in a desired region without directly contacting the substrate, the emitter layer, The first composition can be printed so that the opening and the first conductive layer forming region correspond to each other.

The thickness of the first conductive layer is not particularly limited as long as the conductive metal particles included in the first conductive layer can form a metal silicide by bonding with silicon of the emitter layer. For example, a thickness of about 50 to about 500 nm .

The second composition for forming the second conductive layer may include conductive metal particles, a solvent, a binder, and a dispersant. In addition, components and contents commonly used in this technical field may be applied to the present invention. have.

According to an embodiment of the present invention, the second composition may be at least one selected from the group consisting of Ag, Au, Al, Ni, Pt, Cu, May include at least one selected from the group consisting of silver (Ag), preferably silver (Ag), but the present invention is not limited thereto, Can be used without.

According to one embodiment of the present invention, the second composition may comprise, as conductive metal particles, about 60 to about 95 wt% of silver (Ag), based on the total weight of the second composition. When the silver (Ag) particles are contained in the second composition in an amount of less than 60% by weight, sufficient conductivity may not be obtained in the front electrode. If the silver (Ag) particles are contained in an amount of more than 95% by weight, Which is not desirable.

According to one embodiment of the present invention, the second composition may include glass frit, preferably about 0.01 to about 1.5% by weight based on the total weight of the second composition, more preferably, About 0.01% to about 0.9% by weight. The particle size of the glass frit is not particularly limited, but may be, for example, about 50 nm to about 5 탆. According to the conventional method of manufacturing a solar cell electrode, a conductive transparent electrode layer is formed on the antireflection layer without forming an opening corresponding to the conductive layer, and silver (Ag) contained in the composition for forming the electrode Liquid phase at high temperature and then recrystallized to a solid phase and comes into contact with the emitter layer through a punch through phenomenon penetrating through the antireflection layer via glass frit. Therefore, in a conventional process for forming an electrode by printing with a silver-containing composition, a glass frit is always contained in a composition for forming an electrode in order to form an antireflection layer, and an organic frit, , The produced solar cell adversely affects the electrical conductivity of the electrode and the dispersion stability of the ink, resulting in a reduction in the efficiency of the solar cell. Since the second composition for forming a second conductive layer of the present invention contains glass frit in a certain range or less, there is an advantage that the electrical conductivity is not reduced by the glass frit and the dispersion stability of the ink composition is not greatly affected. Therefore, there is no particular limitation on the particle diameter of the glass frit included in the second composition for forming the second conductive layer. As described above, when the glass frit is included, the efficiency of the solar cell can be improved by making contact between the electrode and the emitter layer in the manufactured solar cell, but the glass frit is about 1.5 If it is contained in an amount of more than 1% by weight, the punch-through phenomenon can be excessively caused on the antireflection layer, which has already been removed to a great extent, and the flow of electrons such as a shunt phenomenon can be changed. The efficiency may be lowered.

The binder and dispersant contained in the second composition are as described above in the first composition.

The solvent contained in the second composition may dissolve the binder and may be mixed with other additives. Examples of such solvents include a-terpinol, butyl cabitol acetate, Texanol, butyl cabitol, or dipropylene glycol monomethyl ether (Di- propylene glycol monomethyl ether), but the present invention is not limited thereto.

In addition, components and contents commonly used in this technical field can be applied to the present invention.

In the preparation of the second composition, the steps of stirring and pulverizing may be performed by a ball milling process, and in particular, a milling process may be used to produce nanoparticles of glass frit. Further, Or particles whose particle diameters are out of range can be used. But it is not limited thereto, and can be produced through a process such as flame spray pyrolysis or plasma treatment.

According to an embodiment of the present invention, the step of forming the second conductive layer may be performed by electrohydrodynamic printing (EHD), silver light induced plating (LIP), screen printing, inkjet printing Inkjet printing, or dispensing, and may preferably include dispensing. When the above dispensing method is used, a conductive layer having a high aspect ratio can be formed by utilizing the second composition, and the efficiency of a manufactured solar cell can be improved.

The A manufacturing method of a solar cell front electrode includes a step of firing the first and second conductive layers.

 According to an embodiment of the present invention, the step of firing the first and second conductive layers may be performed at a temperature of about 400 to about 980 DEG C before the step of forming the second conductive layer after the step of forming the first conductive layer, Preferably at about 840 to about 860 DEG C for 0.1 to 20 minutes and at a temperature of about 400 to about 980 DEG C, preferably about 840 to about 860 DEG C for 0.1 to 20 minutes after the step of forming the first conductive layer And firing.

According to another embodiment of the present invention, the step of firing the first and second conductive layers is performed at a temperature of about 400 to about 980 ° C, preferably about 840 Lt; 0 > C to about 860 < 0 > C for 0.1 to 20 minutes.

The characteristics of the solar cell manufactured according to the firing temperature of the electrode are changed. When the electrode is fired in the temperature range described above, the first conductive layer formed by the first composition and the second conductive layer formed by the second composition So that the efficiency of the produced solar cell is further enhanced.

According to an embodiment of the present invention, the width of the line width of the second conductive layer may correspond to the first conductive layer region, or may include a margin of the line width including the first conductive layer region. The thickness of the second conductive layer may be about 5 占 퐉 to about 25 占 퐉. If the thickness of the formed second conductive layer is less than about 5 탆, the line resistance may increase and the current may be lowered. If the thickness of the second conductive layer exceeds 25 탆, the second conductive layer may cover the sunlight, The efficiency of the solar cell can be lowered due to the lasing shading effect, and the production cost is increased, which is disadvantageous from the economical point of view.

A method of manufacturing a solar cell according to an embodiment of the present invention includes: forming an emitter layer on a substrate; Forming an anti-reflective layer on the emitter layer; Applying an etching paste to a part of the surface of the antireflection layer, and then removing the part of the antireflection layer to form an opening; Printing a first composition for forming a conductive layer on the opening of the antireflection layer by non-contact metallization to form a first conductive layer; Printing a second composition for forming a conductive layer on the first conductive layer to form a second conductive layer; Applying a composition for forming a rear electrode to a back surface of the substrate; And firing.

The method related to electrode formation in the manufacturing method of the solar cell is as described in the manufacturing method of the solar cell front electrode and other processes other than the manufacturing method of the solar cell front electrode are used for manufacturing solar cells in the technical field A general manufacturing method can be applied. For example, after a front electrode is formed, a solar cell may be manufactured by printing a composition including a metal powder for a rear electrode on a rear surface, drying and then firing in a firing furnace to produce a front electrode and a rear electrode have. Alternatively, a method of separately firing each of the electrodes, for example, a method of firing after forming the first conductive layer, firing the second conductive layer, firing the front electrode, and printing a composition including the metal powder for the rear electrode on the back surface , Drying, and firing to produce a back electrode, but the present invention is not limited thereto.

FIG. 1 schematically shows a structure of a solar cell manufactured according to an embodiment of the present invention.

1, a solar cell manufactured according to the manufacturing method of the present invention comprises a substrate 1, an emitter layer 2 formed on the substrate 1, an antireflection layer 3 formed on the emitter layer 2, And a front electrode 6 connected to the emitter layer 2 through the antireflection layer 3 and including a first conductive layer 4 and a second conductive layer 5, And a back electrode 7 connected to the back electrode 7.

The substrate 1 can be doped with impurities such as B, Ga and In, which are P type impurities, as a Group 3 element, and P, As, Sb and the like as a Group 5 element are impurities in the emitter layer 2 Lt; / RTI > P-N junctions are formed at the interface between the substrate 1 and the emitter layer 2 when the substrate 1 and the emitter layer 2 are doped with impurities of the opposite conductivity type.

The antireflection layer 3 immobilizes defects existing in the surface or bulk of the emitter layer 2 and reduces the reflectance of sunlight incident on the front surface of the substrate 1. [ When defects present in the emitter layer 2 are passivated, the recombination sites of the minority carriers are removed to increase the open-circuit voltage (Voc) of the solar cell. When the reflectance of sunlight decreases, the total amount of light reaching the PN junction increases , The short circuit current Isc of the solar cell increases. When the open-circuit voltage and the short-circuit current of the solar cell are increased by the antireflection layer 3, the conversion efficiency of the solar cell is improved accordingly.

On the other hand, as can be seen from FIG. 1, the front electrode 6 is positioned at the uppermost part of the solar cell to cover the sunlight. Therefore, it is important to minimize the area of the front electrode 6 without deteriorating its function.

The rear electrode 7 may include aluminum, but is not limited thereto. For example, the rear electrode 7 may be formed by printing ink on the rear surface of the substrate 1 to which aluminum, quartz silica, a binder, or the like is added, followed by heat treatment. Aluminum may be diffused through the back surface of the substrate 1 during the heat treatment of the back electrode 7 so that a back surface layer may be formed on the interface between the back electrode 7 and the substrate 1 . When the rear front layer is formed, the carrier can be prevented from moving to the rear surface of the substrate 1 and recombining, thereby increasing the open-circuit voltage of the solar cell and improving the efficiency of the entire solar cell.

2 is a schematic diagram of a solar cell manufacturing process according to an embodiment of the present invention.

Referring to FIG. 2, there is shown a method of manufacturing a semiconductor device, comprising: forming an emitter layer 2 on a substrate 1; Forming an anti-reflective layer (3) on the emitter layer (2); Forming an opening by removing the partial area of the antireflection layer (3) after applying an etching paste to a part of the area on the antireflection layer (3); Printing the first composition for forming a conductive layer on the opening of the antireflection layer 3 by non-contact metallization to form the first conductive layer 4; Printing a second composition for forming a conductive layer on the first conductive layer (4) to form a second conductive layer (5); Applying a composition for forming a back electrode to the back surface of the substrate (1); And the step of firing the front electrode 6 and the rear electrode 7 can be performed.

Best Mode for Carrying Out the Invention Hereinafter, the function and effect of the present invention will be described in more detail through specific examples of the present invention. It is to be understood, however, that these embodiments are merely illustrative of the invention and are not intended to limit the scope of the invention.

< Example >

Preparation of first composition

&Lt; Preparation Example 1 &

The first composition contained 20 wt% of nickel (Ni) particles having a size of about 50 nm, 50 wt% of ethyl cellosolve as a main solvent, 27 wt% of Tripropyleneglycol methylether as a high boiling solvent, 1% by weight of an alkylphenol-formaldehyde copolymer and 2% by weight of BYK996 as a dispersing agent, and mixing the mixture with a ball mill for 2 hours

&Lt; Preparation Example 2 &

The first composition was prepared by mixing 10 wt% of nickel (Ni) particles having a size of about 50 nm, 50 wt% of ethyl cellosolve as a main solvent, 27 wt% of Tripropyleneglycol methylether as a high boiling solvent, 1% by weight of an alkylphenol-formaldehyde copolymer and 2% by weight of BYK996 as a dispersing agent, and mixing the mixture with a ball mill for 2 hours

&Lt; Preparation Example 3 &

The first composition contained 40 wt% of nickel (Ni) particles having a size of about 50 nm, 50 wt% of ethyl cellosolve as a main solvent, 27 wt% of Tripropyleneglycol methylether as a high boiling solvent, 1% by weight of an alkylphenol-formaldehyde copolymer and 2% by weight of BYK996 as a dispersing agent, and mixing the mixture with a ball mill for 2 hours

Preparation of second composition

&Lt; Preparation Example 4 &

The silver (Ag) powder contained 59.89 wt% of silver particles (trade name 2-1C) having a mean particle diameter (d50) of 0.8 탆 and 30.16 wt% of silver particles (trade name 4-8F) Respectively.

The glass frit was added so as to contain 0.5% by weight.

As the binder, 2.15% by weight of ethyl cellulose (Dow Std 10), 7.0% by weight of butyl carbitol acetate (BCA) as a solvent and 0.3% by weight of a dispersant (KD-4 of Croda) A composition was prepared.

&Lt; Production Example 5 &

The silver (Ag) powder contained 59.89 wt% of silver particles (trade name 2-1C) having a mean particle size (d50) of 0.8 mu m and 30.66 wt% of silver particles (trade name 4-8F) Respectively.

No glass frit was added.

As the binder, 2.15% by weight of ethyl cellulose (Dow Std 10), 7.0% by weight of butyl carbitol acetate (BCA) as a solvent and 0.3% by weight of a dispersant (KD-4 of Croda) Paste composition.

&Lt; Production Example 6 &

The silver (Ag) powder contained 59.89 wt% of silver particles (trade name 2-1C) having an average particle size (d50) of 0.8 mu m and 29.66 wt% of silver particles (trade name 4-8F) Respectively.

The glass frit was added so as to contain 1% by weight.

As the binder, 2.15% by weight of ethyl cellulose (Dow Std 10), 7.0% by weight of butyl carbitol acetate (BCA) as a solvent and 0.3% by weight of a dispersant (KD-4 of Croda) Paste composition.

Solar cell manufacturing

&Lt; Example 1 >

Phosphorus (P) was doped through a diffusion process using POCL3 at 880 DEG C in a tube furnace using a 156 mm polycrystalline silicon wafer to form an emitter layer having a sheet resistance of 100 OMEGA / sq. A silicon nitride film was deposited on the emitter layer by a plasma enhanced chemical vapor deposition (PECVD) method to have a thickness of 80 nm to form an antireflection layer.

The antireflection layer was printed with a line width of 60 mu m by an electrohydrodynamic printing (EHD) method using an etching paste of SolarEtch BES Type 10 manufactured by Merck Co., then set to 330 DEG C with a belt dryer and dried. The dried wafer was subjected to ultrasonic treatment in a water bath containing 0.1% KOH solution to remove the antireflection layer on which the etching paste had been printed, followed by drying to form openings. A first conductive layer was formed by electrohydrodynamic printing (EHD) using the first composition prepared in Preparation Example 1. This was dried at 60 캜, and a second conductive layer was formed on the formed first conductive layer by dispensing using the second composition prepared in Preparation Example 4.

After the first and second conductive layers were dried at 270 ° C, an Al paste (ALSOLAR T company) was printed on the rear surface. After drying at 200 ° C, the front and rear electrodes were formed by firing in a Belt firing furnace having a maximum temperature of 850 ° C.

&Lt; Example 2 >

A solar cell was manufactured in the same manner as in Example 1, except that the temperature of the belt dryer was set to 310 ° C in the process of forming the opening.

&Lt; Example 3 >

A solar cell was manufactured in the same manner as in Example 1 except that the temperature of the belt dryer was set to 350 ° C in the process of forming the opening.

<Example 4>

A solar cell was prepared in the same manner as in Example 1, except that the first composition for forming the first conductive layer was the one prepared in Preparation Example 2.

&Lt; Example 5 >

A solar cell was prepared in the same manner as in Example 1, except that the first composition for forming the first conductive layer was the one prepared in Preparation Example 3.

&Lt; Example 6 >

A solar cell was prepared in the same manner as in Example 1 except that the second composition for forming the second conductive layer was the one prepared in Preparation Example 5.

&Lt; Example 7 >

A solar cell was prepared in the same manner as in Example 1 except that the second composition for forming the second conductive layer was the one prepared in Preparation Example 6.

&Lt; Example 8 >

A solar cell was manufactured in the same manner as in Example 1 except that the front electrode and the rear electrode were formed by firing in a firing furnace having a maximum temperature of 830 캜 in the firing process.

&Lt; Example 9 >

A solar cell was manufactured in the same manner as in Example 1 except that the front electrode and the back electrode were formed by firing in a Belt firing furnace having a maximum temperature of 870 캜 in the firing process.

&Lt; Comparative Example 1 &

Phosphorus (P) was doped through a diffusion process using POCl ₃ at 880 ° C. in a tube furnace using a 156 mm polysilicon wafer to form an emitter layer having a sheet resistance of 100 Ω / sq. A silicon nitride film was deposited on the emitter layer by a plasma enhanced chemical vapor deposition (PECVD) method to have a thickness of 80 nm to form an antireflection layer.

A conductive layer for the front electrode was formed by screen printing using Sol 9411 (content of glass frit of 2%) of Heraeus Co. commercialized on the antireflection layer.

After the conductive layer was dried at 270 캜, an Al paste (ALSOLAR T company) was printed on the rear surface. After drying at 200 ° C, the front and rear electrodes were formed by firing in a Belt firing furnace having a maximum temperature of 850 ° C.

&Lt; Comparative Example 2 &

A solar cell was manufactured in the same manner as in Example 1 except that the conductive layer for the front electrode was formed using only the second composition without the step of forming the first conductive layer by using the first composition in Example 1 Respectively.

The conditions of each step in the above Examples and Comparative Examples are summarized in Table 1 below.

division Drying temperature
(° C) In the first composition
Nickel content
(weight%) In the second composition
Glass frit content
(weight%) Firing temperature
(° C) Example 1 330 20 0.5 850 Example 2 310 20 0.5 850 Example 3 350 20 0.5 850 Example 4 330 10 0.5 850 Example 5 330 40 0.5 850 Example 6 330 20 0 850 Example 7 330 20 1.0 850 Example 8 330 20 0.5 830 Example 9 330 20 0.5 870 Comparative Example 1 - - 2.0 850 Comparative Example 2 330 - 0.5 850

< Test Example >

Measurement of solar cell efficiency

For the solar cells manufactured according to Examples and Comparative Examples, the solar cell efficiency was measured using ABET Technologies solar simulator having a 150 Watt Xenon arc lamp source. The measurement results are shown in Table 2 below.

Where Jsc means the short circuit current density measured at the zero output voltage and Voc means the open circuit voltage measured at zero output current. FF [%] means fill factor, Eta [%] means efficiency.

division Jsc [mA / cm ² ] Voc [V] FF [%] Eta [%] Example 1 35.38 0.622 77.4 17 Example 2 34.926 0.618 76 16.4 Example 3 35.003 0.617 74.2 16 Example 4 34.843 0.621 76.8 16.7 Example 5 34.965 0.62 74.7 16.2 Example 6 35.09 0.62 74.7 16.3 Example 7 34.829 0.618 73.3 15.8 Example 8 34.836 0.618 72.9 15.7 Example 9 34.794 0.618 69.2 14.9 Comparative Example 1 34.29 0.608 77 16.1 Comparative Example 2 25.608 0.599 29.6 4.5

As can be seen from the results of Table 2, the solar cell manufactured according to the embodiment showed generally superior characteristics to the solar cell manufactured according to the comparative example.

As a result of measurement of the characteristics of the solar cell manufactured by Examples 2 and 3, it was confirmed that the characteristics of the manufactured solar cell varied according to the reaction temperature between the etching paste and the spinneret film. This is related to the degree of reaction between the antireflection layer and the etching paste. When the temperature is lower than the proper temperature as in Example 2, the antireflection layer remains excessively, and contact between the formed electrode and the emitter layer is poor, , And when the temperature is higher than the proper reaction temperature, the etching paste damages the emitter layer and the characteristics thereof are deteriorated. However, it was confirmed that the solar cells produced by the conventional method and the solar cells without the first conductive layer showed better results.

The results of measurement of the characteristics of the solar cell manufactured according to Examples 4 and 5 show that the characteristics of the manufactured solar cell vary depending on the content of nickel (Ni) contained in the first composition. In the case where the content of nickel (Ni) is small, contact between the substrate and the second conductive layer (silver (Ag)) of the electrode is not properly performed in the formed electrode and the content of nickel (Ni) It seems that the electrical conductivity of the conductive layer (nickel (Ni)) is worse than that of the second conductive layer (silver (Ag)), rather it interferes with the electron flow of the electrode. In this case, however, it was confirmed that the solar cell produced by the conventional method and the solar cell not including the first conductive layer showed better results.

The results of the measurement of the characteristics of the solar cell according to Examples 6 and 7 show that the characteristics of the produced solar cell vary depending on the content of the glass frit contained in the second composition. When the glass frit is contained in an amount of 0.5% by weight, the efficiency of the entire solar cell can be improved by the contact between the electrode and the emitter layer where the glass frit is formed. However, when the glass frit is contained in an amount exceeding 1% by weight, Punch through phenomenon may occur in the solar cell, which may change the flow of electrons such as a shunt phenomenon, and the efficiency of the solar cell may be deteriorated accordingly. In this case, however, it was confirmed that the solar cell produced by the conventional method and the solar cell not including the first conductive layer showed better results.

The results of measurement of the characteristics of the solar cell according to Examples 8 and 9 show that the characteristics of the manufactured solar cell vary depending on the firing temperature condition. When the firing maximum temperature was 850 캜, the first composition and the second composition exhibited high efficiency by properly firing the electrode forming material. However, it was confirmed that even when the solar cell was fired at a lower temperature or a higher temperature, the solar cell produced by the conventional method or the solar cell without the first conductive layer showed better results.

1: substrate
2: Emitter layer
3: Antireflection layer
4: the first conductive layer of the front electrode
5: the second conductive layer of the front electrode
6: front electrode
7: Rear electrode

Claims (17)

Forming an emitter layer on the substrate;
Forming an anti-reflective layer on the emitter layer;
Applying an etching paste to a part of the surface of the antireflection layer, and then removing the part of the antireflection layer to form an opening;
Printing a first composition for forming a conductive layer on the opening of the antireflection layer by non-contact metallization to form a first conductive layer;
Printing a second composition for forming a conductive layer on the first conductive layer to form a second conductive layer; And
And firing the first and second conductive layers.
The method of claim 1, wherein the second conductive layer is formed to correspond to a region of the first conductive layer.
The method of claim 1, wherein the etching paste is applied by a non-contact printing method or a screen printing method.
The manufacturing method of a solar cell front electrode according to claim 1, wherein the step of forming the opening further comprises a step of drying the etching paste before applying the etching paste and removing a portion of the antireflection layer .
5. The method of manufacturing a solar cell front electrode according to claim 4, wherein the process of drying the etching paste is performed at 250 to 350 ° C.
The method as claimed in claim 1, wherein the forming of the first conductive layer comprises electrohydrodynamic printing (EHD).
The method of claim 1, wherein the first composition is selected from the group consisting of Ni, Ti, Co, Pt, Pd, Mo, Cr, , Tungsten (W), and an alloy thereof.
The method according to claim 7, wherein the first composition comprises the nickel (Ni) in an amount of 15 to 35% by weight based on the total weight of the first composition.
The method of claim 1, wherein the second composition is selected from the group consisting of silver (Ag), gold (Au), aluminum (Al), nickel (Ni), platinum (Pt), copper Manufacturing method of solar cell front electrode including at least one kind
The method of claim 1, wherein the forming of the second conductive layer comprises forming a first conductive layer on the first conductive layer by electrohydrodynamic printing (EHD), screen printing, inkjet printing, Dispensing. &Lt; / RTI &gt;
The method of claim 1, wherein the second composition comprises glass frit.
12. The method as claimed in claim 11, wherein the second composition comprises glass frit in an amount of 0.01 to 1.5% by weight.
The method according to claim 1, wherein the firing of the first and second conductive layers comprises firing at 400 to 980 캜 for 0.1 to 20 minutes before forming the second conductive layer after forming the first conductive layer And firing at 400 to 980 캜 for 0.1 to 20 minutes after forming the second conductive layer.
The method of claim 1, wherein the firing of the first and second conductive layers comprises: forming all of the first and second conductive layers, followed by firing at 400 to 980 캜 for 0.1 to 20 minutes. A method for manufacturing a front electrode.
The manufacturing method of a solar cell front electrode according to claim 1, wherein the substrate is doped with a P-type impurity, and the emitter layer is doped with an N-type impurity.
The antireflection layer according to claim 1, wherein the antireflection layer is formed of silicon nitride, silicon nitride, silicon oxide, magnesium fluoride (MgF ₂ ), zinc sulfide (ZnS), titanium oxide (TiO ₂ ), cerium oxide (CeO ₂ ) And a mixture thereof. The method of manufacturing a front electrode of a solar cell according to claim 1,
Forming an emitter layer on the substrate;
Forming an anti-reflective layer on the emitter layer;
Applying an etching paste to a part of the surface of the antireflection layer, and then removing the part of the antireflection layer to form an opening;
Printing a first composition for forming a conductive layer on the opening of the antireflection layer by non-contact metallization to form a first conductive layer;
Printing a second composition for forming a conductive layer on the first conductive layer to form a second conductive layer;
Applying a composition for forming a rear electrode to a back surface of the substrate; And
And firing the solar cell.

Images