JPH0563219A - Solar battery and manufacture thereof - Google Patents

Abstract

PURPOSE:To provide a solar battery with satisfactory characteristics and high durability at the time of actual use and a manufacturing method, in which this solar battery can be manufactured with a good yield. CONSTITUTION:In a thin-film solar battery formed by the accumulator of semiconductor layers 103, 104 and 105 on a substrate 101, the upper parts of the semiconductors are coated with a passivation layer 107 composed of high- molecular resin and a collector electrode 108 composed of conductive paste is laminated on the passivation layer. In the manufacture of the thin-film solar battery formed by the accumulation of the semiconductor layers on the substrate, also, the upper parts of the semiconductor layers are coated with the passivation layer composed of the high-molecular resin and the collector electrode composed of the conductive paste containing components capable of dissolving the high-molecular resin is laminated on the passivation layer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solar cell having good reliability and productivity and a method for manufacturing the same.

[0002]

2. Description of the Related Art Solar cells, which are photoelectric conversion elements for converting sunlight into electric energy, have been attracting attention as alternative energy sources for petroleum. Examples of solar cells include single crystal silicon solar cells, amorphous silicon solar cells, and polycrystalline silicon solar cells.

The problem with single crystal silicon is that the production cost is high because a semiconductor process is used as the manufacturing method, and because the single crystal silicon is an indirect transition, the optical absorption coefficient is small, and the single crystal solar The cell must have a thickness of at least 50 microns to absorb incident sunlight, resulting in high material costs and a bandgap of about 1. leV, which is about 5 wavelengths in the solar spectrum
The short wavelength component of 00 nm or less cannot be effectively used due to the problem of surface recombination or the energy of the band gap or less is wasted.

Even if polycrystalline silicon is used to reduce the production cost, the problem of indirect transition remains and the thickness of the solar cell cannot be reduced. Furthermore, polycrystalline silicon has problems such as grain boundaries.

By the way, considering an electric power used in a private house as an example of the existing electric power substitution using a solar cell, the necessary electric power is about 3 KW. On the other hand, the energy from the sun is 1 Kw / m ² at the peak, so the conversion efficiency is 1
If it is 0%, a solar cell of 30 m ² is required. Therefore, in order to use the solar cell for electric power, it is necessary to manufacture a solar cell module having a large area.

However, in the case of single crystal silicon, a wafer having a large area cannot be manufactured and it is difficult to increase the area.
When taking out a large amount of electric power, it is necessary to wire the unit elements in series or in parallel. Furthermore, since monocrystalline silicon is mechanically weak, it protects solar cells from mechanical damage caused by various weather conditions when used outdoors, and is expensive because it is made of glass, polymer resin, aluminum frame, etc. Encapsulation is required. From the above, there is a problem that the production cost per unit power generation amount becomes higher than the existing power generation method.

Under these circumstances, research on an amorphous silicon solar cell that can be manufactured at a low cost and in a large area has been advanced.

FIGS. 4A to 4C show typical examples of conventional solar cells. In the figure, 400 is a solar cell main body, 401 is a substrate, 402 is a lower electrode, 403
Is an n layer, 404 is an i layer, 405 is a p layer, 406 is a transparent electrode, 407 is a passivation layer, 408 is a collector electrode,
Reference numeral 409 represents a bus bar.

The structure of an amorphous silicon solar cell is generally a thin film p layer 405 and i layer 40 on a substrate 401.
4, a transparent electrode 406 for lowering the surface resistance is laminated on one or more semiconductor junctions composed of the n layer 403, and then a collector electrode 408 made of a relatively thin metal for collecting an electric current is formed. Deposited, and further said collector electrode 40
Bus bar 40 for collecting the current collected by 8
An electrode made of a relatively thick metal called 9 is deposited.

A problem arises when such an amorphous silicon solar cell is deposited on a substrate having a large area of, for example, about 30 cm square, or continuously deposited on a long substrate using a roll-to-roll method. This means that pinholes and other defects are generated in the process, which causes shunts and shorts, which reduces the conversion efficiency of the solar cell. The reason for this is that the substrate surface is not a completely smooth surface and scratches or dents
Alternatively, because of the presence of spike-like protrusions or the provision of a convex / concave back reflector for the purpose of irregularly reflecting light on the substrate, a thin semiconductor layer with a thickness of several hundred Å such as p and n layers is used. Such a surface cannot be completely covered, or another cause is that pinholes are generated due to dust during film formation. There is no problem if there is an original normal semiconductor junction between the lower electrode and the upper electrode of the solar cell, but the semiconductor junction is lost due to the above defects and the upper and lower electrodes are in direct contact, or the substrate If the spikes come into contact with the upper electrode or if the semiconductor layer has a low resistance, even if the semiconductor layer is not completely lost, the current generated by light flows into this defective portion, so that the generated current cannot be effectively collected. When the position of such a defect is distant from the current collecting electrode or the bus bar, the resistance when flowing into the defective portion is large, so that the current loss is relatively small, but conversely it is below the current collecting electrode or the bus bar. In some cases, the current lost due to the defect becomes larger.

As a countermeasure against such a shunt or short circuit, only the defective portion is selectively covered with an insulating material or a material having an appropriate high resistance to increase the contact resistance with the transparent electrode, the collecting electrode or the bus bar. Is an effective means to prevent the reduction of conversion efficiency. The best way is to selectively treat only the defective portion, but as a method other than such selective insulation, as shown in FIG. 4C, it is disclosed in US Pat. No. 4,590,327. As described in U.S. Pat. No. 4,633,033 and U.S. Pat. No. 4,633,034, a busbar and a collecting electrode pattern are insulated from each other by a polymer or an oxide. A method of providing a material having a low electric conductivity of 300 Ω / □ or more or an insulating material between the semiconductor layer and the transparent electrode in the corresponding portion has been considered.

However, in the conventional method, since the insulating material or the high-resistance material is arranged in accordance with the pattern of the bus bar or the collecting electrode, it is necessary to pattern the insulating material in the same position as the bus bar and to arrange the same. However, it was not a practical process because it required a patterning step. Further, since the bus bar is laminated on the insulating material or the high resistance material, the adhesive strength is weak and a bus bar adhesive is required.

Further, in the conventional method, the current collecting electrode itself has a resistance instead of providing an insulating material under the current collecting electrode, so that the series resistance of the solar cell becomes large and the conversion efficiency is low. It was Further, in order to avoid such a situation, if only the current collecting electrode is formed by the usual manufacturing method, a large short circuit may occur when there is a defective portion under the current collecting electrode.

Further, even if the initial characteristics of the solar cell module were sufficient, they were not stable against stimuli such as heat, light, and humidity during long-term outdoor use. Therefore, a short circuit may occur during actual use.

[0015]

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems in a pin type thin film solar cell and to provide a solar cell having good characteristics by passivating defects.

Another object of the present invention is to provide a solar cell having good durability in actual use.

Still another object of the present invention is to provide a method for manufacturing a solar cell which has a good characteristic and a high yield by passivating defects in a pin type thin film solar cell.

[0018]

In order to achieve the above-mentioned object, the solar cell of the present invention is a thin film solar cell in which a semiconductor layer is deposited on a substrate. And a current collecting electrode made of a conductive paste is laminated on the passivation layer.

The polymer resin is preferably a component selected from polyester, ethylene vinyl acetate copolymer, acrylic, epoxy and urethane, and has a transmittance of sunlight of 90% or more, and substantially It is desirable to be electrically insulating. Further, it is desirable that the metal component of the conductive paste contains at least one component selected from silver, palladium, copper, carbon and alloys thereof.

The method for producing a solar cell of the present invention is the method for producing a thin film solar cell in which a semiconductor layer is deposited on a substrate, and a passivation layer made of a polymer resin is coated on the semiconductor layer, It is characterized in that a current collecting electrode made of a conductive paste containing a component capable of dissolving the polymer resin is laminated on the passivation layer.

The polymer resin is preferably prepared by a method selected from the group consisting of electrodeposition, electrolytic polymerization, plasma polymerization, spin coating, roll coating and dipping. It is preferable that the component of the conductive paste that dissolves the polymer resin contains at least one of ethyl acetate, methyl ethyl ketone, and toluene, and in some cases, it may be an unreacted component of the polymer resin binder.

[0022]

The function and the structure of the solar cell of the present invention will be described in detail below with reference to the drawings.

FIG. 1 (A) schematically shows a constitutional example of the pin type amorphous solar cell of the present invention. Figure 1
FIG. 1B is a diagram showing a cross-sectional view of FIG. Figure 1
FIG. 1C is a view of FIG. 1A viewed from above.

FIG. 1A shows a solar cell having a structure in which light is incident from the upper part of the figure. In the figure, 100 is a solar cell main body, 101 is a base, 102 is a lower electrode, 103 is an n-type semiconductor layer, and 104 is i layer, 105 p layer, 106 transparent electrode, 107 passivation layer, 108 collector electrode,
Reference numeral 109 represents a bus bar.

The base 101 may be conductive or electrically insulating. Specifically, for example, Fe, Ni, C
r, Al, Mo, Au, Nb, Ta, V, Ti, Pt,
Metals such as Pb or alloys thereof, for example, thin plates such as brass and stainless steel, and composites thereof, and, for example, polyester, polyethylene, polycarbonate, cellulose acetate, polypropylene, polyvinyl chloride, polyvinylidene chloride, polystyrene, polyamide, polyimide, Resin or sheet of heat resistant synthetic resin such as epoxy or a composite of these with glass fiber, carbon fiber, boron fiber, metal fiber, etc., and thin metal plate of these metals, metal thin film of different materials on the surface of resin sheet, etc. / Or, for example, SiO ₂ , Si ₃ N ₄ , Al ₂ O ₃ ,
An insulating thin film such as AlN is formed by, for example, a sputtering method, a vapor deposition method,
Examples thereof include those subjected to surface coating treatment by a plating method, glass, ceramics and the like.

When the substrate 101 is electrically insulating, for example, Al, A or the like is formed on the surface on the side where the deposited film is formed.
g, Pt, Au, Ni, Ti, Mo, W, Fe, V, C
r, Cu, stainless steel, brass, nichrome, Sn
The lower electrode 102 is formed by using a simple metal or alloy such as O ₂ , In ₂ O ₃ , ZnO, and ITO, and a transparent conductive oxide (TCO) by a method such as plating, vapor deposition, and sputtering. Further, even if the substrate 101 is conductive, the lower electrode 102 is manufactured using the same materials and means as described above for the purpose of smoothing or texturing the surface.

The n layer 103, the i layer 104, and the p layer 10 are manufactured by a normal thin film manufacturing process. For example, a vapor deposition method, a sputtering method, a high frequency plasma CVD method, a microwave plasma CVD method, an ECR method, a thermal CVD method. Law, LP
It can be produced by using a known method such as a CVD method as desired. As a method industrially adopted, a plasma CVD method of decomposing a source gas with plasma and depositing it on a substrate is preferably used. Further, as the reaction device, a batch type device, a continuous film forming device, or the like can be used as desired.

The solar cell of the present invention can also be used in a so-called tandem cell in which two or more sets of pin junctions are laminated for the purpose of improving spectral sensitivity and voltage. Examples of the semiconductor material that constitutes the i layer 104 preferably used in the solar cell of the present invention include a-Si: H and a-S.
i: F, a-Si: H: F, a-SiGe: H, a-S
iGe: F, a-SiGe: H: F, a-SiC: H,
So-called IV such as a-SiC: F and a-SiC: H: F
Group II and group IV alloy-based amorphous semiconductors are mentioned.

The semiconductor material forming the p-layer 10 5 or the n-layer 104, which is preferably used in the solar cell of the present invention, is obtained by doping the above-mentioned semiconductor material forming the i-layer 10 4 with a valence electron control agent. .. As the manufacturing method, the same method as the manufacturing method of the i layer 104 described above can be preferably used. In addition, as a raw material, I
When a group V deposited film is obtained, a compound containing an element of group III of the periodic table is used as a valence electron control agent for obtaining a p-type semiconductor. Examples of the group III element include B,
Al, Ga, In, etc. are mentioned.

As the valence electron control agent for obtaining the n-type semiconductor, a compound containing an element of Group V of the periodic table is used.
Examples of the Group V element include P, N, As, and Sb.

The transparent electrode 106 used in the present invention
In order to efficiently absorb sunlight and room light in the semiconductor layer, it is desirable that the light transmittance is 85% or more. Further, electrically, the current generated by the light is laterally applied to the semiconductor layer. Sheet resistance is 10
It is preferably 0Ω / □ or less. Examples of materials having such characteristics include SnO ₂ , In ₂ O ₃ , and Zn.
O, CdO, CdSnO ₄ , ITO (In ₂ O ₃ + Sn
Metal oxides such as O ₂ ) may be mentioned. As a method for manufacturing these, for example, a resistance heating vapor deposition method, an electron beam heating vapor deposition method, a sputtering method, a spray method, or the like can be used, and is appropriately selected as desired.

The passivation layer 107 used in the present invention is an insulating material for preventing a defective portion having a low resistance, which causes a shunt or a short circuit, from coming into contact with the collector electrode 108 and the bus bar 109. Further, since the passivation layer 107 is laminated on the entire surface of the semiconductor layer, it needs to be a light transmissive material so as not to prevent the incidence of sunlight. Considering the environment when used outdoors as a solar cell, it is required to have good weather resistance and stability against heat, humidity and light. Further, in some cases, the solar cell may be bent or impacted, so that it is necessary to have mechanical strength as well.

As such a material, a polymer resin is suitable, and specifically, polyester, ethylene vinyl acetate copolymer, acrylic resin, epoxy resin, urethane or the like is used. A number average molecular weight of the polymer resin is preferably about 1 to 20,000. The film thickness is preferably selected depending on the physical properties of the polymer resin, since it is preferably a film thickness that maintains the insulating property and does not impair the light transmittance.
000Å to 100 μm is suitable, preferably 1
μm to 50 μm, most preferably 5 μm to 20 μm. As a method of laminating such a polymer resin,
Conventional methods are used, for example, methods such as spin coating or dipping by dissolving in a solvent, methods of melting by heat and coating with a roller, methods of depositing by electrolytic polymerization, methods of depositing by electrodeposition, plasma polymerization. The method is used and is appropriately selected from various conditions such as the physical properties of the polymer resin and the desired film thickness. From the viewpoint of mass productivity, the dipping method, roller coating method, electrodeposition method and the like are preferable. In particular, the electrodeposition method is a preferable method because a water-soluble solvent can be used, the treatment of the waste liquid is simple, and the film thickness can be easily controlled by controlling the electric current.

A device for such electrodeposition is shown in FIG. 2 (A), for example.
Alternatively, a device as shown in FIG. 2 (B) can be used. In FIG. 2, 201 is an electrodeposition bath, 202 is an electrodeposition solution, 203 is a counter electrode, 204 is a base, 205 is a transparent electrode, 206 is a power source,
Reference numeral 207 indicates a conducting wire. When electrodeposition is performed, a voltage can be applied to the base body 204 of the solar cell, and in some cases, a voltage may be applied by providing an appropriate terminal on the transparent electrode 205. In the latter case, since no voltage is applied to the inside of the solar cell, unnecessary current does not flow in the solar cell and the solar cell is not destroyed during the electrodeposition process, and the back side of the base body 204 is not electrodeposited. Moreover, there is an effect that the speed of electrodeposition can be increased and the electrodeposition liquid can be saved.

As the electrodeposition liquid 202, a commercially available one can be used, and there are anion type and cation type, but the substrate 2
Since the polarity of the voltage applied to 04 is different, it may be selected as necessary.

Current collecting electrode 10 used in the present invention
Is a low resistance electrode for collecting the current flowing through the transparent electrode 10 6. Examples of the electrode material include Ag, Pt,
A so-called conductive paste is prepared by mixing a conductive filler such as Cu and C or a powder of an alloy thereof with a binder of a polymer resin such as epoxy, polyester and urethane and a solvent of the binder at an appropriate ratio to form a paste. Be done. As for the desired specific resistance, it is necessary that a sufficient current flows when plating is performed, and it is desirable to have 10 ⁻² Ω.
cm to 10 ⁻⁵ Ωcm, and a commercially available conductive paste can be appropriately selected and used.
As a commercially available product, for example, a silver filler is used and the binder is polyester, and a product manufactured by DuPont 500
There are No. 7 and Fujikura Kasei FC-301CA. Examples of silver fillers having an epoxy binder include Ablebond No. 84-1LM-1 and No. 959-1. For the silver filler and polyurethane binder, there are three bond No. 3322 and 3320.
There is D number. A suitable solvent may be added to these conductive pastes to adjust the viscosity.

The electrodes of these conductive pastes can be produced with high productivity by using the conventionally known screen printing method. In the screen printing method, a conductive paste is used as a printing ink by using a screen in which a desired pattern is formed on a mesh of nylon or stainless steel, and the electrode width can be about 50 μm at the minimum.
Commercially available printers such as Hk-4060 manufactured by Tokai Seiki are preferably used. The screen-printed conductive paste is heated in a drying oven to crosslink the binder and volatilize the solvent.

In the present invention, the passivation layer 1
It is necessary to select a conductive paste material according to the physical properties of 07. That is, since the passivation layer 107 is insulative or has high resistance, the ohmic contact between the current collecting electrode 108 and the transparent electrode 106 is not sufficient even if the current collecting electrode 108 is laminated thereon, but it is included in the conductive paste. The solvent or the monomer dissolves the passivation layer 107 and the conductive filler comes into contact with the transparent electrode 106, so that the current collecting electrode 108 and the transparent electrode 106 come into sufficient contact with each other. In this case, the defective portion and the conductive filler may come into contact with each other at the same time, but since the binder and the passivation layer 107, which cannot be completely dissolved by the solvent, cover the defective portion, an appropriate resistance occurs and the degree of short circuit is reduced.

The shape and area of the collector electrode 108 are appropriately designed so as not to prevent light from entering the semiconductor layer and to efficiently collect current. That is, the area is made to be a minimum so as not to be shaded by the incidence of light, and the conductivity is made as good as possible so as not to become a resistance to an electric current. The bus bar 109 used in the present invention is an electrode for further collecting the current flowing through the collector electrode 108. As the electrode material, for example, a metal such as Ag, Pt, or Cu, or a material made of C or an alloy thereof can be used, and a wire-shaped or foil-shaped material can be stuck or a conductive sheet similar to that of the current collecting electrode 108. You may use a strike. As the foil-shaped one, for example, a copper foil, or a copper foil tin-plated, and an adhesive-attached one is used in some cases. As such, for example, a commercially available 3M product 13
Number 45 or the like is used. Further, since a large current flows through the bus bar, it is necessary to make the cross-sectional area larger than that of the current collecting electrode so that the resistance is low. The solar cell produced as described above is modularized by encapsulation by a conventionally known method in order to improve weather resistance when used outdoors.

As the material for encapsulation, EVA (ethylene vinyl acetate) is preferably used as an adhesive layer from the viewpoints of adhesiveness to solar cells, weather resistance and buffering effect. Further, in order to further improve moisture resistance and scratch resistance, a fluorine resin is laminated as a surface protection layer. As the fluorine-based resin, for example, a polymer T of tetrafluoroethylene T
FE (Teflon manufactured by DuPont, etc.), tetrafluoroethylene-ethylene copolymer ETFE (Tefzel manufactured by DuPont, etc.), polyvinyl fluoride (Tedlar manufactured by DuPont, etc.),
Examples thereof include polychlorofluoroethylene CTFE (Neotron produced by Daikin Industries). The weather resistance may be improved by adding an ultraviolet absorber to these resins.

A method of laminating these resins on a solar cell substrate can be carried out by heating and pressure bonding in a vacuum using a commercially available apparatus such as a vacuum laminator (VTL-100 type manufactured by Nippon Phystech Co., Ltd.). is there. The structure of the solar cell module of the present invention thus manufactured is as shown in FIG. In the figure, 300 is a solar cell module main body, 301 is a base, 302 is a lower electrode, 303 is an n-type semiconductor layer, 304 is an i layer, and 305 is p.
A layer, 306 a transparent electrode, 307 a passivation layer,
308 is a collector electrode, 309 is a bus bar, 310 is an adhesive layer, and 311 is a surface protective layer.

As described above, the passivation layer made of polymer resin is provided between the semiconductor layer of the solar cell and the collector electrode above the semiconductor layer, and the collector electrode is formed by using the conductive paste. By doing so, it is possible to prevent a defective portion of the semiconductor layer that causes a shunt or a short circuit from coming into contact with the collector electrode. as a result,
Photocurrent loss due to short circuit is prevented, and a solar cell with high conversion efficiency can be obtained. That is, at the time of applying the conductive paste, the solvent contained in the paste or the monomer of the polymer resin binder partially dissolves the passivation, and the conductive filler makes an electrical contact for contacting the transparent electrode and the current collecting electrode. At the same time, since the passivation and the polymer resin binder cover the defective portion, the short circuit can be suppressed.

Further, the adhesion of the passivation layer formed as described above to the collector electrode is high, and the adhesion to the encapsulation material is also high, so that the durability of the solar cell is greatly improved. Further, the configuration of the present invention described above simplifies the manufacturing process, such as the need for the passivation patterning process, and makes it possible to manufacture solar cells with a high yield.

[0044]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples.

Example 1 A solar cell having the layer structure shown in FIG. 1A was manufactured as follows.

First, SUS4 that has been thoroughly degreased and washed
Substrate made of 30BA (30 cm square, thickness 0.1 mm) 101
Was placed in a DC sputter device (not shown) to deposit 2000 liters of Cr to form the lower electrode 102. The substrate 101 was taken out, placed in an RF plasma CVD film forming apparatus (not shown), and the n layer 103, the i layer 104, and the p layer 105 were deposited in this order.
Then, it was placed in a resistance heating vapor deposition apparatus (not shown), and an alloy of In and Sn was vapor-deposited by resistance heating to deposit 700 Å of a transparent conductive film 106 having a function also as an antireflection effect. Next, the passivation layer 107 was deposited using the electrodeposition apparatus of FIG. 2 in the following procedure.

First, deionized water is placed in the electrodeposition tank 201 at a rate of 10
Acrylic anion electrodeposition coating (Acrylic Clear A manufactured by Uemura Kogyo Co., Ltd.)
-7X) was added in 2 liters. After continuing stirring for 1 hour, it was left standing for 2 days for aging to prepare an electrodeposition liquid 202. Next, the substrate 101 is put into the electrodeposition tank 201,
A voltage of 30 V was applied to the counter electrode 203 so that the substrate 204 became negative, and the voltage was maintained for 2 minutes. After depositing the passivation layer 107 on the transparent electrode 106, the substrate 101 was taken out from the electrodeposition bath, washed with deionized water, placed in a thermostat and kept at 150 ° C. for 5 minutes to dry the passivation layer 107. When the film thickness of this film was measured by a stylus film thickness meter, it was 5 μm. Further, this film was an insulating film whose resistance value was so large that it could not be measured even by using the HP Micro Ammeter 4140B. Further, when the film was deposited on a mirror-finished silver plate and the light transmittance was measured by reflection measurement, it was 90% or more.

Next, the substrate 101 is set on a screen printer (Tokai Seiki HK-4060) not shown, and the width is 300 μm.
A current collecting electrode lO8 having a length of m and a length of 8 cm was printed at an interval of 1 cm. At this time, the conductive paste is 70 parts of Ag filler,
A composition having 30 parts (volume ratio) of a polyester binder and 5 parts of ethyl acetate as a solvent was used. After printing, the substrate 101 was placed in a thermostat and held at 150 ° C. for 5 minutes to cure the conductive paste. Furthermore, width 5 with adhesive
A 30 cm square single cell was prepared by adhering a bus bar lO9 of a copper foil (No. 1345 manufactured by 3M) of mm as shown in FIG. 1 (C).

Next, encapsulation of this sample was performed as follows. EVA (ethylene vinyl acetate) is laminated on the upper and lower sides of the substrate 101, and further, PTFE (polytetrafluoroethylene) resin (Tefzel manufactured by DuPont) is further laminated on the upper and lower sides thereof, and then a vacuum laminator (VTL-100 type manufactured by Nippon Phystech Equipment Co., Ltd.) Throw in 15
Hold at 0 ° C. for 60 minutes to carry out vacuum lamination.
The obtained sample was It was set to 1-1.

The initial characteristics of the obtained sample were measured as follows. First, the voltage-current characteristics of the obtained sample were measured in the dark state, and the shunt resistance was measured from the slope near the origin. Next, using each of the above samples, a pseudo solar light source (hereinafter referred to as a simulator) using a xenon lamp was used. 5
The solar cell spectrum was irradiated with an intensity of 100 mW / cm ² to measure the solar cell characteristics, and the conversion efficiency was obtained. The series resistance was determined from the current-voltage curve at this time.

Next, in order to evaluate the difference due to the composition of the conductive paste used for the collecting electrode 108, the passivation layer 107 is formed on another substrate 101 by the method described above, and the composition of the conductive paste is changed variously. Collector electrode 108
Formed. Subsequent steps were also performed in the same manner as the above-mentioned method, encapsulation was performed, and evaluation was performed in the same manner as above.

Sample No. 1-2 to No. Sample Nos. Up to 1-4. The amount of the solvent was changed with the same binder as in 1-1, and the composition and the evaluation results are shown in Table 1. Sample No. 1-5 to No. Up to 1-8, the binder is polyurethane and the solvent is methyl ethyl ketone (ME
As K), the amount of the solvent was changed, and the results are shown in Table 2. Sample No. 1-9 to No. Up to 1-12, the amount of the solvent was changed with epoxy as the binder and MEK as the solvent, and the results are shown in Table 3.

As shown in Tables 1 and 2, the solar cell characteristics greatly differ depending on the amount of solvent. When the amount of solvent is large, the shunt resistance and series resistance are small, and when the amount of solvent is small, the shunt resistance and series resistance are small. Is big. this is,
When the amount of the solvent is small, it is considered that the passivation layer 107 is melted and Ag is less likely to come into contact with the transparent electrode 106, and the series resistance increases, but at the same time, leakage current can be prevented and the shunt resistance increases. On the other hand, when the amount of the solvent is large, the passivation layer 107 is excessively melted, the contact area between Ag and the transparent electrode 106 is large, the passivation effect is almost lost, the leak current is increased, the shunt resistance is reduced, and the transparent electrode 108 and the transparent electrode 108 are transparent. It is interpreted that the series resistance is small because the contact resistance with the electrode 1O6 is small.

On the other hand, in the case of Table 3, good conversion efficiency is obtained even in the absence of a solvent, and the shunt resistance and series resistance become smaller as the amount of the solvent is increased, but in this case, the monomer in the binder is the passivation layer. It is thought that this is because it has a dissolving effect. Next, among these samples, the sample No. having good initial characteristics was used. 1-3, No. 1-
7, No. The variations in initial characteristics and durability characteristics of 1-10 were evaluated as follows. First, N
o. 1-3, No. 1-7, No. Ten samples each corresponding to No. 1-10 were prepared, and No. 1-20 to N
o. 29, No. 1-30 to No. 1-39, No. 1
-40 to No. It was set to 1-49. These initial characteristics were measured, and the results are shown in Table 4. As shown in Table 4, it can be seen that there is little variation in characteristics and the yield is good.

Next, the durability characteristics are Japanese Industrial Standard C8917.
The temperature-humidity cycle test A-2 defined in the environmental test method and the durability test method for the crystalline solar cell module was performed.

First, the sample is placed in a thermo-hygrostat whose temperature and humidity can be controlled, and the temperature is from −40 ° C. to + 85 ° C. (85% relative humidity).
The cycle test of changing to 10 was repeated 10 times. The solar cell characteristics of the sample after the test were measured using a shunt resistance and a simulator in the dark state in the same manner as the measurement of the initial characteristics. The results are shown in Table 4, respectively.

As is clear from Table 4, no deterioration was observed after the durability test and it was found that there was a good passivation effect. Further, no peeling between the encapsulation resin and the substrate was observed, and it was found that the passivation layer 107 had a good adhesive effect.

From the above results, it is understood that the solar cell of the present invention using the method for producing a solar cell of the present invention has a good yield, excellent durability, and high reliability.

[0059]

[Table 1]

[0060]

[Table 2]

[0061]

[Table 3]

[0062]

[Table 4] (Comparative Example 1) A conventional solar cell having the layer structure shown in FIG. 4 (A) was produced as follows.

As in Example 1, the transparent electrode 406 was formed on the substrate 401. Next, the passivation layer 40
7 was manufactured by the electrodeposition method in the same manner as in Example 1. The difference from Example 1 is that the passivation layer 407 is patterned. Further, the collector electrode 408 was printed in the same manner as in Example 1. At this time, as the conductive paste, Fujikura Kasei FC-301CA No. was used. Further, a bus bar 409 of copper foil with an adhesive was laminated on the passivation layer 407 to prepare a single cell of 30 cm square.

Ten samples were manufactured by the above manufacturing method. Next, encapsulation of this sample was performed in the same manner as in Example 1. The obtained samples were designated as R-1 to R-10.

The initial characteristics of the obtained sample were that the conversion efficiency was 5.2% ± 2% and the shunt resistance was 150 to ⁵ KΩcm ^2.
In comparison with Example 1, the variation was large and the shunt was large.

Next, the durability characteristics of this sample were evaluated in the same manner as in Example 1. When the solar cell characteristics of the sample after the completion of the temperature / humidity cycle test were measured, it was 90% on average with respect to the initial value, and significant deterioration occurred. Also, from R-1 to R-1
When the shunt resistance of 0 was measured, it was 50% smaller on average.

The shunt portion of this sample was confirmed as follows. A reverse bias of 1.5 volts was applied to the sample. Electric current flows into the shunt area and heat is generated, but normal area does not generate heat because current does not flow because of reverse bias. When the surface of the sample was observed with an infrared camera in this state, a heat generating part was observed and it was found that the sample was shunted under the collecting electrode. Further, there was a partial peeling between the encapsulation resin and the substrate. (Comparative Example 2) A solar cell provided with a conventional passivation layer shown in FIG. 4 (B) was produced as follows.

Similar to the first embodiment, the p-layer 40 is formed on the substrate 401.
Up to 5 were formed. Next, a positive pattern mask having the same shape as the bus bar 409 made of polyester film is laminated on the p-layer 405, the passivation layer 407 is electrodeposited in the same manner as in Example 1, and the passivation layer 407 is formed on the p-layer 405. Was formed in the same pattern as the bus bar 409. Next, a current collecting electrode 408 was printed by a screen printer (not shown) in the same manner as in Comparative Example 1. Further, a copper foil with an adhesive was laminated as a bus bar 409, and then a transparent electrode 406 was deposited to produce a 30 cm square single cell. Ten samples were prepared as described above.

Next, the encapsulation of this sample was performed in the same manner as in Example 1. The obtained samples were designated as R-20 to R-20. The initial characteristics of the obtained sample are a conversion efficiency of 5.8 ± 1.5% and a shunt resistance of 200 to 15 KΩc.
m ² and the variation was large and the shunt was large compared to Example 1. The series resistance was determined to be 30 to 10 Ωcm ² .

Next, the durability characteristics of this sample were evaluated in the same manner as in Example 1. When the solar cell characteristics of the sample after the completion of the temperature / humidity cycle test were measured, it was 90% on average with respect to the initial value, and significant deterioration occurred. Further, when the shunt resistance of the sample was measured, it was reduced by an average of about 30%, indicating that the sample was shunted.

When the shunt portion of this sample was observed with an infrared camera in the same manner as in Comparative Example 1, it was found that the sample was shunted under the collecting electrode.

Example 2 Next, the passivation layer 10
7 was manufactured from a cationic electrodeposition resin, and a solar cell having a layer structure shown in FIG. 1 (A) was manufactured in substantially the same manner as in Example 1.

First, in the same manner as in Example 1, the transparent electrode 106 was formed on the substrate 101. Next, the passivation layer 107 was deposited by cation electrodeposition according to the following procedure.

First, 10 liters of deionized water was placed in the electrodeposition tank 201 shown in FIG. 2 while stirring at a speed of 100 rpm to produce an epoxy anion electrodeposition paint (AUED80 manufactured by Uemura Kogyo).
1 liter of 0-FH) was added. After stirring for 1 hour, the mixture was left standing for 2 days for aging. Next, the substrate 10
1 was placed in the electrodeposition tank 201, a voltage of 100 V was applied to the counter electrode 202 so that the substrate 101 became positive, and the voltage was held for 2 minutes. After depositing the passivation layer 107 on the transparent electrode 106, the substrate 101 was taken out of the electrodeposition bath, washed with deionized water, placed in a thermostat and kept at 175 ° C. for 20 minutes to dry the passivation layer 107. When the film thickness of this film was measured with a stylus type film thickness meter, it was 10
was μm.

Next, in the same manner as in Example 1, 60 parts of Pd filler, 40 parts of epoxy (volume ratio), and MEK as a solvent.
Collector electrode 1 using a conductive paste having a composition containing 15 parts of
08 was printed and copper foil with an adhesive was laminated on the bus bar 109 to prepare a 30 cm square single cell. Ten sheets of the above sample were produced.

Further, the encapsulation of this sample was performed in the same manner as in Example 1. The obtained sample was Two
-1 to No. It was set to 2-10. The initial characteristics of the obtained sample are 6.1% ± 0.5% and the shunt resistance is 500 KΩ.
It was cm ^{2 to} 300 KΩcm ² , and the characteristics were good, and the variation was small.

Next, the durability characteristics of this sample were evaluated in the same manner as in Example 1. When the solar cell characteristics of the sample after the temperature-humidity cycle test were measured, the average initial conversion efficiency was 9
It was 7%, and no significant deterioration occurred. When the shunt resistance was measured, the decrease was about 10%, and there was no significant deterioration. Further, no peeling between the encapsulation resin and the substrate was observed, and it was found that the passivation layer 107 had a good adhesive effect.

From the results of this example, it can be seen that the solar cell of the present invention manufactured by the solar cell manufacturing method of the present invention has a good yield, good characteristics, and good durability.

Example 3 Next, the passivation layer 1
The manufacturing method of 07 is changed to the dip coating method, and FIG.
A solar cell having the layer structure shown in was prepared as follows.

In the same manner as in Example 1, transparent electrodes 106 were formed on the base electrode 10l. Next, a polyester resin having a number average molecular weight of 1 to 20,000 was dissolved in the solvent MEK. The substrate 10l was put into this tank, pulled up, and kept at 70 ° C for 5 minutes in a thermostat to dry the solvent to form a passivation layer 107. The thickness of the passivation layer 107 was 5 μm.

Next, in the same manner as in Example 1, the collector electrode 108.
Was printed and a copper foil with an adhesive was laminated on a bus bar 109 to prepare a 30 cm square single cell. Similarly, 10 samples were prepared.

Further, the encapsulation of this sample was performed in the same manner as in Example 1. The obtained sample was Three
-1 to No. It was set to 3-10. The initial characteristics of the obtained sample are 6.3% ± 0.7% and the shunt resistance is 300 KΩ.
cm ^{2 to} 100 KΩcm ² , with good characteristics and little variation.

Next, the durability characteristics of this sample were evaluated in the same manner as in Example 1. When the solar cell characteristics of the sample after the temperature / humidity cycle test were measured, the average conversion efficiency was 9 with respect to the initial conversion efficiency.
It was 8%, and no significant deterioration occurred. When the shunt resistance was measured, the decrease was about 10%, and there was no significant deterioration.

Further, no peeling between the encapsulation resin and the substrate was observed, and it was found that the passivation layer 107 had a good adhesive effect.

From the results of this example, it is understood that the solar cell of the present invention manufactured by the solar cell manufacturing method of the present invention has a good yield, good characteristics, and good durability.

[0086]

The solar cell of the present invention is a thin film solar cell in which at least a pair of semiconductor junctions are deposited on a substrate, and a passivation layer made of a polymer resin is coated on the semiconductor and the passivation layer is formed. A structure in which a collector electrode made of a conductive paste is laminated on the ionization layer, and the polymer resin is a component selected from polyester, ethylene vinyl acetate copolymer, acrylic, epoxy, and urethane, and sunlight. With a transmittance of 90% or more to substantially insulative, the metal component of the conductive paste contains at least one component of silver, palladium, copper, and carbon, thereby providing good durability. An excellent solar cell can be provided.

Further, according to the method for manufacturing a solar cell of the present invention, in the method for manufacturing a thin film solar cell in which at least a pair of semiconductor junctions are deposited on a substrate, a passivation layer made of a polymer resin is provided on the semiconductor layer. A coating is performed, and a current collecting electrode made of a conductive paste containing a component capable of dissolving the polymer resin is laminated on the passivation layer. As a method for producing a polymer resin, an electrodeposition method,
Using a method selected from electrolytic polymerization method, plasma polymerization method, spin coating method, roll coating method and dipping method, the component of the conductive paste that dissolves the polymer resin is ethyl acetate, methyl ethyl ketone, or toluene. By including at least one, a solar cell can be manufactured with a high yield.

[Brief description of drawings]

FIG. 1 is a perspective view schematically showing the structure of a solar cell of the present invention.

FIG. 2 is a diagram showing an apparatus for an electrodeposition method.

FIG. 3 is a diagram showing a solar cell module of the present invention.

FIG. 4 is a diagram schematically showing a configuration of a conventional solar cell.

[Explanation of symbols]

 100, 300, 400 solar cell main body, 101, 301, 401 substrate, 102, 302, 402 lower electrode, 103, 303, 403 n layer, 104, 304, 404 i layer, 105, 305, 405 p layer, 106, 306, 406 transparent electrode, 107, 307, 407 passivation layer, 108, 308, 408 current collecting electrode, 109, 309, 409 bus bar 201 electrodeposition bath, 202 electrodeposition liquid, 203 counter electrode, 204 substrate, 205 semiconductor layer, 206 power supply, 207 conducting wire, 310 adhesive layer, 311 surface protection layer.

Claims (12)

[Claims] 1. In a thin-film solar cell comprising a semiconductor layer deposited on a substrate, a passivation layer made of a polymer resin is coated on the semiconductor layer, and a conductive paste is formed on the passivation layer. A solar cell comprising a plurality of stacked collector electrodes. 2. The solar cell according to claim 1, wherein the polymer resin comprises a component selected from polyester, ethylene vinyl acetate copolymer, acrylic, epoxy and polyurethane. 3. The solar cell according to claim 1, wherein the polymer resin has a transmittance of sunlight of 90% or more.
The solar cell according to. 4. The solar cell according to claim 1, wherein the polymer resin is substantially insulating. 5. The conductive paste is silver, palladium,
2. At least one of conductive fillers made of copper, carbon or alloys thereof is contained.
5. The solar cell according to any one of items 4 to 4. 6. The solar cell according to claim 1, wherein the conductive paste contains at least one binder made of polyester, epoxy or polyurethane. 7. A method of manufacturing a thin film solar cell comprising a semiconductor layer deposited on a substrate, wherein a passivation layer made of a polymer resin is coated on the semiconductor layer,
A method of manufacturing a solar cell, comprising: stacking a collector electrode made of a conductive paste containing a component capable of dissolving the polymer resin on the passivation layer. 8. The polymer resin is an electrodeposition method, an electrolytic polymerization method,
The method of manufacturing a solar cell according to claim 7, wherein the method is formed by a method selected from a plasma polymerization method, a spin coating method, a roll coating method, and a dipping method. 9. The conductive paste is silver, palladium,
9. The method for manufacturing a solar cell according to claim 7, comprising at least one of conductive fillers made of copper, carbon, or an alloy thereof. 10. The conductive paste is polyester,
The method for manufacturing a solar cell according to claim 7, further comprising at least one of binders made of epoxy or polyurethane. 11. The conductive paste-containing component capable of dissolving the polymer resin is at least one of ethyl acetate, methyl ethyl ketone, and toluene, according to claim 7. The method for manufacturing a solar cell according to. 12. The method of manufacturing a solar cell according to claim 10, wherein the binder contains an unreacted component.